changeset 8d92c2737ac8 in /z/repo/m5
details: http://repo.m5sim.org/m5?cmd=changeset;node=8d92c2737ac8
description:
cache: fix dirty bit setting
Only set the dirty bit when we actually write to a block
(not if we thought we might but didn't, as in a failed
SC or CAS). This requires makeing sure the dirty bit
stays set when we get an exclusive (writable) copy
in a cache-to-cache transfer from another owner, which
n turn requires copying the mem-inhibit flag from
timing-mode requests to their associated responses.
diffstat:
src/mem/cache/cache_impl.hh | 29 ++++++++++++++++-------------
src/mem/packet.hh | 4 ++++
2 files changed, 20 insertions(+), 13 deletions(-)
diffs (76 lines):
diff -r b26258d233d2 -r 8d92c2737ac8 src/mem/cache/cache_impl.hh
--- a/src/mem/cache/cache_impl.hh Tue Jun 15 14:00:41 2010 -0700
+++ b/src/mem/cache/cache_impl.hh Wed Jun 16 15:25:57 2010 -0700
@@ -1,5 +1,6 @@
/*
* Copyright (c) 2002-2005 The Regents of The University of Michigan
+ * Copyright (c) 2010 Advanced Micro Devices, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -169,9 +170,9 @@
if (pkt->cmd == MemCmd::SwapReq) {
cmpAndSwap(blk, pkt);
} else if (pkt->isWrite()) {
- blk->status |= BlkDirty;
if (blk->checkWrite(pkt)) {
pkt->writeDataToBlock(blk->data, blkSize);
+ blk->status |= BlkDirty;
}
} else if (pkt->isRead()) {
if (pkt->isLLSC()) {
@@ -988,11 +989,19 @@
assert(pkt->hasData() || blk->isValid());
}
+ blk->status = BlkValid | BlkReadable;
+
if (!pkt->sharedAsserted()) {
- blk->status = BlkValid | BlkReadable | BlkWritable;
- } else {
- assert(!pkt->needsExclusive());
- blk->status = BlkValid | BlkReadable;
+ blk->status |= BlkWritable;
+ // If we got this via cache-to-cache transfer (i.e., from a
+ // cache that was an owner) and took away that owner's copy,
+ // then we need to write it back. Normally this happens
+ // anyway as a side effect of getting a copy to write it, but
+ // there are cases (such as failed store conditionals or
+ // compare-and-swaps) where we'll demand an exclusive copy but
+ // end up not writing it.
+ if (pkt->memInhibitAsserted())
+ blk->status |= BlkDirty;
}
DPRINTF(Cache, "Block addr %x moving from state %i to %i\n",
@@ -1023,14 +1032,8 @@
{
// timing-mode snoop responses require a new packet, unless we
// already made a copy...
- PacketPtr pkt = already_copied ? req_pkt : new Packet(req_pkt, true);
- if (!req_pkt->isInvalidate()) {
- // note that we're ignoring the shared flag on req_pkt... it's
- // basically irrelevant, as we'll always assert shared unless
- // it's an exclusive request, in which case the shared line
- // should never be asserted1
- pkt->assertShared();
- }
+ PacketPtr pkt = already_copied ? req_pkt : new Packet(req_pkt);
+ assert(req_pkt->isInvalidate() || pkt->sharedAsserted());
pkt->allocate();
pkt->makeTimingResponse();
if (pkt->isRead()) {
diff -r b26258d233d2 -r 8d92c2737ac8 src/mem/packet.hh
--- a/src/mem/packet.hh Tue Jun 15 14:00:41 2010 -0700
+++ b/src/mem/packet.hh Wed Jun 16 15:25:57 2010 -0700
@@ -559,6 +559,10 @@
origCmd = cmd;
cmd = cmd.responseCommand();
+ // responses are never express, even if the snoop that
+ // triggered them was
+ flags.clear(EXPRESS_SNOOP);
+
dest = src;
flags.set(VALID_DST, flags.isSet(VALID_SRC));
flags.clear(VALID_SRC);
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