f26a289295
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.
111 lines
3.9 KiB
C++
111 lines
3.9 KiB
C++
/*
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* Copyright (c) 2012 ARM Limited
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* All rights reserved.
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2006 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ali Saidi
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* Andreas Hansson
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*/
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#ifndef __MEM_TPORT_HH__
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#define __MEM_TPORT_HH__
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/**
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* @file
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*
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* Declaration of SimpleTimingPort.
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*/
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#include "mem/qport.hh"
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/**
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* The simple timing port uses a queued port to implement
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* recvFunctional and recvTimingReq through recvAtomic. It is always a
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* slave port.
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*/
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class SimpleTimingPort : public QueuedSlavePort
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{
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private:
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/**
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* The packet queue used to store outgoing responses. Note that
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* the queue is made private and that we avoid overloading the
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* name used in the QueuedSlavePort. Access is provided through
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* the queue reference in the base class.
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*/
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RespPacketQueue queueImpl;
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protected:
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/** Implemented using recvAtomic(). */
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void recvFunctional(PacketPtr pkt);
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/** Implemented using recvAtomic(). */
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bool recvTimingReq(PacketPtr pkt);
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virtual Tick recvAtomic(PacketPtr pkt) = 0;
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/**
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* @todo this is a temporary workaround until the 4-phase code is committed.
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* upstream caches need this packet until true is returned, so hold it for
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* deletion until a subsequent call
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*/
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std::vector<PacketPtr> pendingDelete;
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public:
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/**
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* Create a new SimpleTimingPort that relies on a packet queue to
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* hold responses, and implements recvTimingReq and recvFunctional
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* through calls to recvAtomic. Once a request arrives, it is
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* passed to recvAtomic, and in the case of a timing access any
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* response is scheduled to be sent after the delay of the atomic
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* operation.
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*
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* @param name port name
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* @param owner structural owner
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*/
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SimpleTimingPort(const std::string& name, MemObject* owner);
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virtual ~SimpleTimingPort() { }
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};
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#endif // __MEM_TPORT_HH__
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