From 041ea8107e4250a9c120a6fde11f3dc415c2fe6a Mon Sep 17 00:00:00 2001 From: Andreas Hansson Date: Thu, 17 Mar 2016 09:51:18 -0400 Subject: mem: Create a separate class for the cache write buffer 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. --- src/mem/cache/write_queue.hh | 97 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 src/mem/cache/write_queue.hh (limited to 'src/mem/cache/write_queue.hh') diff --git a/src/mem/cache/write_queue.hh b/src/mem/cache/write_queue.hh new file mode 100644 index 000000000..006d70556 --- /dev/null +++ b/src/mem/cache/write_queue.hh @@ -0,0 +1,97 @@ +/* + * Copyright (c) 2015-2016 ARM Limited + * All rights reserved. + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer; + * redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution; + * neither the name of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * Authors: Andreas Hansson + */ + +/** + * @file Declaration of a queue structure to manage uncacheable write + * and writebacks. + */ + +#ifndef __MEM_CACHE_WRITE_QUEUE_HH__ +#define __MEM_CACHE_WRITE_QUEUE_HH__ + +#include + +#include "mem/cache/queue.hh" +#include "mem/cache/write_queue_entry.hh" + +/** + * A write queue for all eviction packets, i.e. writebacks and clean + * evictions, as well as uncacheable writes. + */ +class WriteQueue : public Queue +{ + + public: + + /** + * Create a write queue with a given number of entries. + * @param num_entries The number of entries in this queue. + * @param reserve The maximum number of entries needed to satisfy + * any access. + */ + WriteQueue(const std::string &_label, int num_entries, int reserve); + + /** + * Allocates a new WriteQueueEntry for the request and size. This + * places the request as the first target in the WriteQueueEntry. + * + * @param blk_addr The address of the block. + * @param blk_size The number of bytes to request. + * @param pkt The original write. + * @param when_ready When is the WriteQueueEntry be ready to act upon. + * @param order The logical order of this WriteQueueEntry + * + * @return The a pointer to the WriteQueueEntry allocated. + * + * @pre There are free entries. + */ + WriteQueueEntry *allocate(Addr blk_addr, unsigned blk_size, + PacketPtr pkt, Tick when_ready, Counter order); + + /** + * Mark the given entry as in service. This removes the entry from + * the readyList or deallocates the entry if it does not expect a + * response (writeback/eviction rather than an uncacheable write). + * + * @param entry The entry to mark in service. + */ + void markInService(WriteQueueEntry *entry); +}; + +#endif //__MEM_CACHE_WRITE_QUEUE_HH__ -- cgit v1.2.3