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path: root/src/mem/cache/mshr_queue.hh
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2016-03-17mem: Adjust cache queue reserve to more conservative valuesAndreas Hansson
The cache queue reserve is there as an overflow to give us enough headroom based on when we block the cache, and how many transactions we may already have accepted before actually blocking. The previous values were probably chosen to be "big enough", when we actually know that we check the MSHRs after every single allocation, and for the write buffers we know that we implicitly may need one entry for every outstanding MSHR. * * * mem: Adjust cache queue reserve to more conservative values The cache queue reserve is there as an overflow to give us enough headroom based on when we block the cache, and how many transactions we may already have accepted before actually blocking. The previous values were probably chosen to be "big enough", when we actually know that we check the MSHRs after every single allocation, and for the write buffers we know that we implicitly may need one entry for every outstanding MSHR.
2016-03-17mem: Create a separate class for the cache write bufferAndreas Hansson
This patch breaks out the cache write buffer into a separate class, without affecting any stats. The goal of the patch is to avoid encumbering the much-simpler write queue with the complex MSHR handling. In a follow on patch this simplification allows us to implement write combining. The WriteQueue gets its own class, but shares a common ancestor, the generic Queue, with the MSHRQueue.
2015-12-31mem: Make cache terminology easier to understandAndreas Hansson
This patch changes the name of a bunch of packet flags and MSHR member functions and variables to make the coherency protocol easier to understand. In addition the patch adds and updates lots of descriptions, explicitly spelling out assumptions. The following name changes are made: * the packet memInhibit flag is renamed to cacheResponding * the packet sharedAsserted flag is renamed to hasSharers * the packet NeedsExclusive attribute is renamed to NeedsWritable * the packet isSupplyExclusive is renamed responderHadWritable * the MSHR pendingDirty is renamed to pendingModified The cache states, Modified, Owned, Exclusive, Shared are also called out in the cache and MSHR code to make it easier to understand.
2015-12-28mem: Remove unused cache squash functionalityAndreas Hansson
This patch removes the unused squash function from the MSHR queue, and the associated (and also unused) threadNum member from the MSHR.
2015-11-06mem: Add cache clusivityAndreas Hansson
This patch adds a parameter to control the cache clusivity, that is if the cache is mostly inclusive or exclusive. At the moment there is no intention to support strict policies, and thus the options are: 1) mostly inclusive, or 2) mostly exclusive. The choice of policy guides the behaviuor on a cache fill, and a new helper function, allocOnFill, is created to encapsulate the decision making process. For the timing mode, the decision is annotated on the MSHR on sending out the downstream packet, and in atomic we directly pass the decision to handleFill. We (ab)use the tempBlock in cases where we are not allocating on fill, leaving the rest of the cache unaffected. Simple and effective. This patch also makes it more explicit that multiple caches are allowed to consider a block writable (this is the case also before this patch). That is, for a mostly inclusive cache, multiple caches upstream may also consider the block exclusive. The caches considering the block writable/exclusive all appear along the same path to memory, and from a coherency protocol point of view it works due to the fact that we always snoop upwards in zero time before querying any downstream cache. Note that this patch does not introduce clean writebacks. Thus, for clean lines we are essentially removing a cache level if it is made mostly exclusive. For example, lines from the read-only L1 instruction cache or table-walker cache are always clean, and simply get dropped rather than being passed to the L2. If the L2 is mostly exclusive and does not allocate on fill it will thus never hold the line. A follow on patch adds the clean writebacks. The patch changes the L2 of the O3_ARM_v7a CPU configuration to be mostly exclusive (and stats are affected accordingly).
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.
2015-03-27mem: Align all MSHR entries to block boundariesAndreas Hansson
This patch aligns all MSHR queue entries to block boundaries to simplify checks for matches. Previously there were corner cases that could lead to existing entries not being identified as matches. There are, rather alarmingly, a few regressions that change with this patch.
2015-02-03mem: Clarify cache behaviour for pending dirty responsesAndreas Hansson
This patch adds a bit of clarification around the assumptions made in the cache when packets are sent out, and dirty responses are pending. As part of the change, the marking of an MSHR as in service is simplified slightly, and comments are added to explain what assumptions are made.
2014-12-23mem: Add parameter to reserve MSHR entries for demand accessMitch Hayenga
Adds a new parameter that reserves some number of MSHR entries for demand accesses. This helps prevent prefetchers from taking all MSHRs, forcing demand requests from the CPU to stall.
2014-05-09mem: Squash prefetch requests from downstream cachesMitch Hayenga
This patch squashes prefetch requests from downstream caches, so that they do not steal cachelines away from caches closer to the cpu. It was originally coded by Mitch Hayenga and modified by Aasheesh Kolli.
2014-01-24mem: Add support for a security bit in the memory systemGiacomo Gabrielli
This patch adds the basic building blocks required to support e.g. ARM TrustZone by discerning secure and non-secure memory accesses.
2013-05-30mem: Spring cleaning of MSHR and MSHRQueueAndreas Hansson
This patch does some minor tidying up of the MSHR and MSHRQueue. The clean up started as part of some ad-hoc tracing and debugging, but seems worthwhile enough to go in as a separate patch. The highlights of the changes are reduced scoping (private) members where possible, avoiding redundant new/delete, and constructor initialisation to please static code analyzers.
2012-11-02mem: Add support for writing back and flushing cachesAndreas Sandberg
This patch adds support for the following optional drain methods in the classical memory system's cache model: memWriteback() - Write back all dirty cache lines to memory using functional accesses. memInvalidate() - Invalidate all cache lines. Dirty cache lines are lost unless a writeback is requested. Since memWriteback() is called when checkpointing systems, this patch adds support for checkpointing systems with caches. The serialization code now checks whether there are any dirty lines in the cache. If there are dirty lines in the cache, the checkpoint is flagged as bad and a warning is printed.
2011-04-15includes: sort all includesNathan Binkert
2011-01-07Replace curTick global variable with accessor functions.Steve Reinhardt
This step makes it easy to replace the accessor functions (which still access a global variable) with ones that access per-thread curTick values.
2010-09-09cache: coherence protocol enhancements & bug fixesSteve Reinhardt
Allow lower-level caches (e.g., L2 or L3) to pass exclusive copies to higher levels (e.g., L1). This eliminates a lot of unnecessary upgrade transactions on read-write sequences to non-shared data. Also some cleanup of MSHR coherence handling and multiple bug fixes.
2008-02-10Fix #include lines for renamed cache files.Steve Reinhardt
--HG-- extra : convert_revision : b5008115dc5b34958246608757e69a3fa43b85c5
2008-02-10Rename cache files for brevity and consistency with rest of tree.Steve Reinhardt
--HG-- rename : src/mem/cache/base_cache.cc => src/mem/cache/base.cc rename : src/mem/cache/base_cache.hh => src/mem/cache/base.hh rename : src/mem/cache/cache_blk.cc => src/mem/cache/blk.cc rename : src/mem/cache/cache_blk.hh => src/mem/cache/blk.hh rename : src/mem/cache/cache_builder.cc => src/mem/cache/builder.cc rename : src/mem/cache/miss/mshr.cc => src/mem/cache/mshr.cc rename : src/mem/cache/miss/mshr.hh => src/mem/cache/mshr.hh rename : src/mem/cache/miss/mshr_queue.cc => src/mem/cache/mshr_queue.cc rename : src/mem/cache/miss/mshr_queue.hh => src/mem/cache/mshr_queue.hh rename : src/mem/cache/prefetch/base_prefetcher.cc => src/mem/cache/prefetch/base.cc rename : src/mem/cache/prefetch/base_prefetcher.hh => src/mem/cache/prefetch/base.hh rename : src/mem/cache/prefetch/ghb_prefetcher.cc => src/mem/cache/prefetch/ghb.cc rename : src/mem/cache/prefetch/ghb_prefetcher.hh => src/mem/cache/prefetch/ghb.hh rename : src/mem/cache/prefetch/stride_prefetcher.cc => src/mem/cache/prefetch/stride.cc rename : src/mem/cache/prefetch/stride_prefetcher.hh => src/mem/cache/prefetch/stride.hh rename : src/mem/cache/prefetch/tagged_prefetcher.cc => src/mem/cache/prefetch/tagged.cc rename : src/mem/cache/prefetch/tagged_prefetcher.hh => src/mem/cache/prefetch/tagged.hh rename : src/mem/cache/tags/base_tags.cc => src/mem/cache/tags/base.cc rename : src/mem/cache/tags/base_tags.hh => src/mem/cache/tags/base.hh rename : src/mem/cache/tags/Repl.py => src/mem/cache/tags/iic_repl/Repl.py rename : src/mem/cache/tags/repl/gen.cc => src/mem/cache/tags/iic_repl/gen.cc rename : src/mem/cache/tags/repl/gen.hh => src/mem/cache/tags/iic_repl/gen.hh rename : src/mem/cache/tags/repl/repl.hh => src/mem/cache/tags/iic_repl/repl.hh extra : convert_revision : ff7a35cc155a8d80317563c45cebe405984eac62