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path: root/src/mem/dram_ctrl.hh
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2018-05-18mem: Add support for more flexible DRAM timing and topologiesWendy Elsasser
This patch has 2 main aspects: 1) Add new parameter to adjust write-to-write delay 2) Enable support of more than 64 banks per controller Changes for new parameter: Incorporated a new parameter, tCCD_L_WR, which defaults to tCCD_L. This parameter can be used to set a unique delay between writes and between reads. To incorporate this parameter in the controller, modified the DRAMCtrl class to have separate variables for read and write column delays. Used these variables to account for tRTW, tWTR, tBURST, tCCD_L, and tCS as well as the new tCCD_L_WR parameter. Changes to support more than 64 banks: Modified the logic selecting the next command (reorderQueue and minBankPrep functions). Replaced the unint64_t variables with a vector of uint32_t elements. There is a uint32_t element defined per ranks to allow up to 32 banks per rank. This will automatically scale with ranks without issue. Change will allow analysis of memory sub-systems beyond the current landscape. Change-Id: I0ce466efed58276f843ad90e9ecc0ece6c37d646 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-on: https://gem5-review.googlesource.com/10103 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
2018-05-18mem: Optimize self-refresh entryWendy Elsasser
Self-refresh is entered during a refresh event, when the rank was previously in a precharge power-down state. The original code would enter self-refresh after a refresh was issued. The device subsequently will issue a refresh on self-refresh entry. On self-refresh exit, the controller will issue another refresh command. Devices require at least one additional refresh to be issued between self-refresh exit and re-entry. This ensures that enough refreshes occur in the case when the device narrowly missed a refresh on self-refresh exit. To minimize the number of refresh operations and still maintain the device requirement, the current logic does the following: 1) The controller will still enter self-refresh from a refresh event, when the previous state was precharge power-down. However, the refresh itself will be bypassed and the controller will immediately issue a self-refresh entry. 2) On a self-refresh exit, the controller will immediately issue a refresh command (per the original logic). This ensures the devices requirements are met and is a convenient way to kick off the command state machine. Change-Id: I1c4b0dcbfa3bdafd755f3ccd65e267fcd700c491 Reviewed-by: Curtis Dunham <curtis.dunham@arm.com> Reviewed-on: https://gem5-review.googlesource.com/10102 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
2017-11-16ext, mem: Pull DRAMPower SHA 90d6290 and rebaseRadhika Jagtap
This patch syncs the DRAMPower library of gem5 to the external github (https://github.com/ravenrd/DRAMPower). The version pulled in is the commit: 90d6290f802c29b3de9e10233ceee22290907ce6 from 30th Oct. 2016. This change also modifies the DRAM Ctrl interaction with the DRAMPower, due to changes in the lib API in the above version. Previously multiple functions were called to prepare the power lib before calling the function that would calculate the enery. With the new API, these functions are encompassed inside the function to calculate the energy and therefore should now be removed from the DRAM controller. The other key difference is the introduction of a new function called calcWindowEnergy which can be useful for any system that wants to do measurements over intervals. For gem5 DRAM ctrl that means we now need to accumulate the window energy measurements into the total stat. Change-Id: I3570fff2805962e166ff2a1a3217ebf2d5a197fb Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/5724 Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com> Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2017-06-20mem: Replace EventWrapper use with EventFunctionWrapperSean Wilson
NOTE: With this change there is a possibility for `DRAMCtrl::Rank`s event names to not properly match the rank they were generated by. This could occur if the public rank member is modified after the Rank's construction. A patch would mean refactoring Rank and `DRAMCtrl`b to privatize many of the members of Rank behind getters. Change-Id: I7b8bd15086f4ffdfd3f40be4aeddac5e786fd78e Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3745 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
2017-06-20mem: Move the Rank construction logic to the Rank constructorSean Wilson
This change was made so Rank objects have their name assigned when they are instantiated. Therefore, they can initialize their member objects with their name and it is less likely to change during runtime. (NOTE: I would recommend hiding the fields which would cause the name to change behind getters. Since modification of `Rank.rank` during runtime will cause the `name()` to change.) Change-Id: Id51c3553b40e489792c57950e18b8ce927e43173 Signed-off-by: Sean Wilson <spwilson2@wisc.edu> Reviewed-on: https://gem5-review.googlesource.com/3742 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
2016-10-13mem: Add DRAM low-power functionalityWendy Elsasser
Added power-down state transitions to the DRAM controller model. Added per rank parameter, outstandingEvents, which tracks the number of outstanding command events and is used to determine when the controller should transition to a low power state. The controller will only transition when there are no outstanding events scheduled and the number of command entries for the given rank is 0. The outstandingEvents parameter is incremented for every RD/WR burst, PRE, and REF event scheduled. ACT is implicitly covered by RD/WR since burst will always issue and complete after a required ACT. The parameter is decremented when the event is serviced (completed). The controller will automatically transition to ACT power down, PRE power down, or SREF. Transition to ACT power down state scheduled from: 1) The RespondEvent, where read data is received from the memory. ACT power-down entry will be scheduled when one or more banks is open, all commands for the rank have completed (no more commands scheduled), and there are no commands in queue for the rank Transition to PRE power down scheduled from: 1) respondEvent, when all banks are closed, all commands have completed, and there are no commands in queue for the rank 2) prechargeEvent when all banks are closed, all commands have completed, and there are no commands in queue for the rank 3) refreshEvent, after the refresh is complete when the previous state was ACT power-down 4) refreshEvent, after the refresh is complete when the previous state was PRE power-down and there are commands in the queue. Transition to SREF will be scheduled from: 1) refreshEvent, after the refresh is completes when the previous state was PRE power-down with no commands in queue Power-down exit commands are scheduled from: 1) The refreshEvent, prior to issuing a refresh 2) doDRAMAccess, to wake-up the rank for RD/WR command issue. Self-refresh exit commands are scheduled from: 1) The next request event, when the queue has commands for the rank in the readQueue or there are commands for the rank in the writeQueue and the bus state is WRITE. Change-Id: I6103f660776e36c686655e71d92ec7b5b752050a Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>
2016-10-13mem: Add callback to compute stats prior to dump eventWendy Elsasser
The per rank statistics are periodically updated based on state transition and refresh events. Add a method to update these when a dump event occurs to ensure they reflect accurate values. Specifically, need to ensure that the low-power state durations, power, and energy are logged correctly. Change-Id: Ib642a6668340de8f494a608bb34982e58ba7f1eb Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>
2016-10-13mem: Modify drain to ensure banks and power are idledWendy Elsasser
Add constraint that all ranks have to be in PWR_IDLE before signaling drain complete This will ensure that the banks are all closed and the rank has exited any low-power states. On suspend, update the power stats to sync the DRAM power logic The logic maintains the location of the signalDrainDone method, which is still triggered from either: 1) Read response event 2) Next request event This ensures that the drain will complete in the READ bus state and minimizes the changes required. Change-Id: If1476e631ea7d5999fe50a0c9379c5967a90e3d1 Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>
2016-10-13mem: Sort memory commands and update DRAMPowerWendy Elsasser
Add local variable to stores commands to be issued. These commands are in order within a single bank but will be out of order across banks & ranks. A new procedure, flushCmdList, sorts commands across banks / ranks, and flushes the sorted list, up to curTick() to DRAMPower. This is currently called in refresh, once all previous commands are guaranteed to have completed. Could be called in other events like the powerEvent as well. By only flushing commands up to curTick(), will not get out of sync when flushed at a periodic stats dump (done in subsequent patch). Change-Id: I4ac65a52407f64270db1e16a1fb04cfe7f638851 Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>
2016-10-13mem: add DRAM powerdown timingOmar Naji
2016-07-01ext: Update DRAMPowerMatthias Jung
Sync DRAMPower to external tool This patch syncs the DRAMPower library of gem5 to the external one on github (https://github.com/ravenrd/DRAMPower) of which I am a maintainer. The version used is the commit: 902a00a1797c48a9df97ec88868f20e847680ae6 from 07. May. 2016. Committed by Jason Lowe-Power <jason@lowepower.com>
2015-11-06mem: Unify delayed packet deletionAndreas Hansson
This patch unifies how we deal with delayed packet deletion, where the receiving slave is responsible for deleting the packet, but the sending agent (e.g. a cache) is still relying on the pointer until the call to sendTimingReq completes. Previously we used a mix of a deletion vector and a construct using unique_ptr. With this patch we ensure all slaves use the latter approach.
2015-10-12misc: Add explicit overrides and fix other clang >= 3.5 issuesAndreas Hansson
This patch adds explicit overrides as this is now required when using "-Wall" with clang >= 3.5, the latter now part of the most recent XCode. The patch consequently removes "virtual" for those methods where "override" is added. The latter should be enough of an indication. As part of this patch, a few minor issues that clang >= 3.5 complains about are also resolved (unused methods and variables).
2015-10-12misc: Remove redundant compiler-specific definesAndreas Hansson
This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap (and similar) abstractions, as these are no longer needed with gcc 4.7 and clang 3.1 as minimum compiler versions.
2015-07-07sim: Refactor and simplify the drain APIAndreas Sandberg
The drain() call currently passes around a DrainManager pointer, which is now completely pointless since there is only ever one global DrainManager in the system. It also contains vestiges from the time when SimObjects had to keep track of their child objects that needed draining. This changeset moves all of the DrainState handling to the Drainable base class and changes the drain() and drainResume() calls to reflect this. Particularly, the drain() call has been updated to take no parameters (the DrainManager argument isn't needed) and return a DrainState instead of an unsigned integer (there is no point returning anything other than 0 or 1 any more). Drainable objects should return either DrainState::Draining (equivalent to returning 1 in the old system) if they need more time to drain or DrainState::Drained (equivalent to returning 0 in the old system) if they are already in a consistent state. Returning DrainState::Running is considered an error. Drain done signalling is now done through the signalDrainDone() method in the Drainable class instead of using the DrainManager directly. The new call checks if the state of the object is DrainState::Draining before notifying the drain manager. This means that it is safe to call signalDrainDone() without first checking if the simulator has requested draining. The intention here is to reduce the code needed to implement draining in simple objects.
2015-07-03mem: Update DRAM command scheduler for bank groupsWendy Elsasser
This patch updates the command arbitration so that bank group timing as well as rank-to-rank delays will be taken into account. The resulting arbitration no longer selects commands (prepped or not) that cannot issue seamlessly if there are commands that can issue back-to-back, minimizing the effect of rank-to-rank (tCS) & same bank group (tCCD_L) delays. The arbitration selects a new command based on the following priority. Within each priority band, the arbitration will use FCFS to select the appropriate command: 1) Bank is prepped and burst can issue seamlessly, without a bubble 2) Bank is not prepped, but can prep and issue seamlessly, without a bubble 3) Bank is prepped but burst cannot issue seamlessly. In this case, a bubble will occur on the bus Thus, to enable more parallelism in subsequent selections, an unprepped packet is given higher priority if the bank prep can be hidden. If the bank prep cannot be hidden, the selection logic will choose a prepped packet that cannot issue seamlessly if one exist. Otherwise, the default selection will choose the packet with the minimum bank prep delay.
2015-07-03mem: Avoid DRAM write queue iteration for merging and read lookupAndreas Hansson
This patch adds a simple lookup structure to avoid iterating over the write queue to find read matches, and for the merging of write bursts. Instead of relying on iteration we simply store a set of currently-buffered write-burst addresses and compare against these. For the reads we still perform the iteration if we have a match. For the writes, we rely entirely on the set. Note that there are corner-cases where sub-bursts would actually not be mergeable without a read-modify-write. We ignore these cases and opt for speed.
2015-03-02mem: Split port retry for all different packet classesAndreas Hansson
This patch fixes a long-standing isue with the port flow control. Before this patch the retry mechanism was shared between all different packet classes. As a result, a snoop response could get stuck behind a request waiting for a retry, even if the send/recv functions were split. This caused message-dependent deadlocks in stress-test scenarios. The patch splits the retry into one per packet (message) class. Thus, sendTimingReq has a corresponding recvReqRetry, sendTimingResp has recvRespRetry etc. Most of the changes to the code involve simply clarifying what type of request a specific object was accepting. The biggest change in functionality is in the cache downstream packet queue, facing the memory. This queue was shared by requests and snoop responses, and it is now split into two queues, each with their own flow control, but the same physical MasterPort. These changes fixes the previously seen deadlocks.
2014-12-23mem: Ensure DRAM controller is idle when in atomic modeAndreas Hansson
This patch addresses an issue seen with the KVM CPU where the refresh events scheduled by the DRAM controller forces the simulator to switch out of the KVM mode, thus killing performance. The current patch works around the fact that we currently have no proper API to inform a SimObject of the mode switches. Instead we rely on drainResume being called after any switch, and cache the previous mode locally to be able to decide on appropriate actions. The switcheroo regression require a minor stats bump as a result.
2014-12-23mem: Add rank-wise refresh to the DRAM controllerOmar Naji
This patch adds rank-wise refresh to the controller, as opposed to the channel-wide refresh currently in place. In essence each rank can be refreshed independently, and for this to be possible the controller is extended with a state machine per rank. Without this patch the data bus is always idle during a refresh, as all the ranks are refreshing at the same time. With the rank-wise refresh it is possible to use one rank while another one is refreshing, and thus the data bus can be kept busy. The patch introduces a Rank class to encapsulate the state per rank, and also shifts all the relevant banks, activation tracking etc to the rank. The arbitration is also updated to consider the state of the rank.
2014-10-20mem: Add DRAM device size and check against configOmar Naji
This patch adds the size of the DRAM device to the DRAM config. It also compares the actual DRAM size (calculated using information from the config) to the size defined in the system. If these two values do not match gem5 will print a warning. In order to do correct DRAM research the size of the memory defined in the system should match the size of the DRAM in the config. The timing and current parameters found in the DRAM configs are defined for a DRAM device with a specific size and would differ for another device with a different size.
2014-07-29mem: DRAMPower integration for on-line DRAM power statsOmar Naji
This patch takes the final step in integrating DRAMPower and adds the appropriate calls in the DRAM controller to provide the command trace and extract the power and energy stats. The debug printouts are still left in place, but will eventually be removed. At the moment the DRAM power calculation is always on when using the DRAM controller model. The run-time impact of this addition is around 1.5% when looking at the total host seconds of the regressions. We deem this a sensible trade-off to avoid the complication of adding an enable/disable mechanism.
2014-09-20mem: Add DDR4 bank group timingWendy Elsasser
Added the following parameter to the DRAMCtrl class: - bank_groups_per_rank This defaults to 1. For the DDR4 case, the default is overridden to indicate bank group architecture, with multiple bank groups per rank. Added the following delays to the DRAMCtrl class: - tCCD_L : CAS-to-CAS, same bank group delay - tRRD_L : RAS-to-RAS, same bank group delay These parameters are only applied when bank group timing is enabled. Bank group timing is currently enabled only for DDR4 memories. For all other memories, these delays will default to '0 ns' In the DRAM controller model, applied the bank group timing to the per bank parameters actAllowedAt and colAllowedAt. The actAllowedAt will be updated based on bank group when an ACT is issued. The colAllowedAt will be updated based on bank group when a RD/WR burst is issued. At the moment no modifications are made to the scheduling.
2014-09-20mem: Add memory rank-to-rank delayWendy Elsasser
Add the following delay to the DRAM controller: - tCS : Different rank bus turnaround delay This will be applied for 1) read-to-read, 2) write-to-write, 3) write-to-read, and 4) read-to-write command sequences, where the new command accesses a different rank than the previous burst. The delay defaults to 2*tCK for each defined memory class. Note that this does not correspond to one particular timing constraint, but is a way of modelling all the associated constraints. The DRAM controller has some minor changes to prioritize commands to the same rank. This prioritization will only occur when the command stream is not switching from a read to write or vice versa (in the case of switching we have a gap in any case). To prioritize commands to the same rank, the model will determine if there are any commands queued (same type) to the same rank as the previous command. This check will ensure that the 'same rank' command will be able to execute without adding bubbles to the command flow, e.g. any ACT delay requirements can be done under the hoods, allowing the burst to issue seamlessly.
2014-08-26mem: Update DRAM controller commentsAndreas Hansson
Update comments and add a reference for more information.
2014-08-26mem: Fix address interleaving bug in DRAM controllerAndreas Hansson
This patch fixes a bug in the DRAM controller address decoding. In cases where the DRAM burst size (e.g. 32 bytes in a rank with a single LPDDR3 x32) was smaller than the channel interleaving size (e.g. systems with a 64-byte cache line) one address bit effectively got used as a channel bit when it should have been a low-order column bit. This patch adds a notion of "columns per stripe", and more clearly deals with the low-order column bits and high-order column bits. The patch also relaxes the granularity check such that it is possible to use interleaving granularities other than the cache line size. The patch also adds a missing M5_CLASS_VAR_USED to the tCK member as it is only used in the debug build for now.
2014-06-30mem: DRAMPower trace outputAndreas Hansson
This patch adds a DRAMPower flag to enable off-line DRAM power analysis using the DRAMPower tool. A new DRAMPower flag is added and a follow-on patch adds a Python script to post-process the output and order it based on time stamps. The long-term goal is to link DRAMPower as a library and provide the commands through function calls to the model rather than first printing and then parsing the commands. At the moment it is also up to the user to ensure that the same DRAM configuration is used by the gem5 controller model and DRAMPower.
2014-06-30mem: Add bank and rank indices as fields to the DRAM bankAndreas Hansson
This patch adds the index of the bank and rank as a field so that we can determine the identity of a given bank (reference or pointer) for the power tracing. We also grab the opportunity of cleaning up the arguments used for identifying the bank when activating.
2014-06-30mem: Extend DRAM row bits from 16 to 32 for larger densitiesAndreas Hansson
This patch extends the DRAM row bits to 32 to support larger density memories. Additional checks are also added to ensure the row fits in the 32 bits.
2014-05-09mem: Add DRAM cycle timeAndreas Hansson
This patch extends the current timing parameters with the DRAM cycle time. This is needed as the DRAMPower tool expects timestamps in DRAM cycles. At the moment we could get away with doing this in a post-processing step as the DRAMPower execution is separate from the simulation run. However, in the long run we want the tool to be called during the simulation, and then the cycle time is needed.
2014-05-09mem: Simplify DRAM response schedulingAndreas Hansson
This patch simplifies the DRAM response scheduling based on the assumption that they are always returned in order.
2014-05-09mem: Remove printing of DRAM paramsAndreas Hansson
This patch removes the redundant printing of DRAM params.
2014-05-09mem: Add tRTP to the DRAM controllerAndreas Hansson
This patch adds the tRTP timing constraint, governing the minimum time between a read command and a precharge. Default values are provided for the existing DRAM types.
2014-05-09mem: Merge DRAM latency calculation and bank state updateAndreas Hansson
This patch merges the two control paths used to estimate the latency and update the bank state. As a result of this merging the computation is now in one place only, and should be easier to follow as it is all done in absolute (rather than relative) time. As part of this change, the scheduling is also refined to ensure that we look at a sensible estimate of the bank ready time in choosing the next request. The bank latency stat is removed as it ends up being misleading when the DRAM access code gets evaluated ahead of time (due to the eagerness of waking the model up for scheduling the next request).
2014-05-09mem: Add tWR to DRAM activate and precharge constraintsAndreas Hansson
This patch adds the write recovery time to the DRAM timing constraints, and changes the current tRASDoneAt to a more generic preAllowedAt, capturing when a precharge is allowed to take place. The part of the DRAM access code that accounts for the precharge and activate constraints is updated accordingly.
2014-05-09mem: Add DRAM power states to the controllerAndreas Hansson
This patch adds power states to the controller. These states and the transitions can be used together with the Micron power model. As a more elaborate use-case, the transitions can be used to drive the DRAMPower tool. At the moment, the power-down modes are not used, and this patch simply serves to capture the idle, auto refresh and active modes. The patch adds a third state machine that interacts with the refresh state machine.
2014-05-09mem: Ensure DRAM refresh respects timingsAndreas Hansson
This patch adds a state machine for the refresh scheduling to ensure that no accesses are allowed while the refresh is in progress, and that all banks are propely precharged. As part of this change, the precharging of banks of broken out into a method of its own, making is similar to how activations are dealt with. The idle accounting is also updated to ensure that the refresh duration is not added to the time that the DRAM is in the idle state with all banks precharged.
2014-05-09mem: Make DRAM read/write switching less conservativeAndreas Hansson
This patch changes the read/write event loop to use a single event (nextReqEvent), along with a state variable, thus joining the two control flows. This change makes it easier to follow the state transitions, and control what happens when. With the new loop we modify the overly conservative switching times such that the write-to-read switch allows bank preparation to happen in parallel with the bus turn around. Similarly, the read-to-write switch uses the introduced tRTW constraint.
2014-03-23mem: Track DRAM read/write switching and add hysteresisAndreas Hansson
This patch adds stats for tracking the number of reads/writes per bus turn around, and also adds hysteresis to the write-to-read switching to ensure that the queue does not oscilate around the low threshold.
2014-03-23mem: Rename SimpleDRAM to a more suitable DRAMCtrlAndreas Hansson
This patch renames the not-so-simple SimpleDRAM to a more suitable DRAMCtrl. The name change is intended to ensure that we do not send the wrong message (although the "simple" in SimpleDRAM was originally intended as in cleverly simple, or elegant). As the DRAM controller modelling work is being presented at ISPASS'14 our hope is that a broader audience will use the model in the future. --HG-- rename : src/mem/SimpleDRAM.py => src/mem/DRAMCtrl.py rename : src/mem/simple_dram.cc => src/mem/dram_ctrl.cc rename : src/mem/simple_dram.hh => src/mem/dram_ctrl.hh