mem: Perform write merging in the DRAM write queue

Information
Submitter:	Andreas Hansson
Repository:	gem5
Branch:	default
Bugs:
Depends On:
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Groups:	Default
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Description

Changeset 9834:4c25c3045a75
---------------------------
mem: Perform write merging in the DRAM write queue

This patch implements basic write merging in the DRAM to avoid
redundant bursts. When a new access is added to the queue it is
compared against the existing entries, and if it is either
intersecting or immediately succeeding/preceeding an existing item it
is merged.

There is currently no attempt made at avoiding iterating over the
existing items in determining whether merging is possible or not.

Testing Done

With the Alpha quiesce patch and stats updates all regressions pass.

With this patch, some changes to addToReadQueue() is needed. The reason is that codes in addToReadQueue currently check to see if the starting address of a read packet is the same as that of a write packet in the write queue (my earlier patch considers the packet size as well). With this new patch, we should simply check to see if a read packet falls into boundaries of a write packet.

Andreas Hansson Aug. 6, 2013, 10:35 a.m. (Aug. 6, 2013, 10:35 a.m.)

True. I also need to add a check to ensure we don't merge packets that are already burst size. Will bump the patch.

Andreas Hansson Aug. 7, 2013, 10:24 a.m. (Aug. 7, 2013, 10:24 a.m.)
```
Have a look Amin and see if you're happy with the patch.
```

Description:

~		Changeset 9830:58ba238410d5
	~	Changeset 9831:b5aed07974d4

		mem: Perform write merging in the DRAM write queue

		This patch implements basic write merging in the DRAM to avoid
		redundant bursts. When a new access is added to the queue it is
		compared against the existing entries, and if it is either
		intersecting or immediately succeeding/preceeding an existing item it
		is merged.

		There is currently no attempt made at avoiding iterating over the
		existing items in determining whether merging is possible or not.

Diff:

Revision 2 (+73 -15)

Show changes

	src/mem/simple_dram.hh
	src/mem/simple_dram.cc

Ship It!

Amin Farmahini Aug. 7, 2013, 11:03 a.m. (Aug. 7, 2013, 11:03 a.m.)

Thanks!
Just a suggestion, since dramPkt size should be always smaller than or equal burstSize, it would be good if we add a couple of assertions in the code like "assert(dram_pkt->size <= burstSize)" or assert(size <= burstSize) to make sure this is never violated.

Description:

~		Changeset 9831:b5aed07974d4
	~	Changeset 9834:4c25c3045a75

		mem: Perform write merging in the DRAM write queue

		This patch implements basic write merging in the DRAM to avoid
		redundant bursts. When a new access is added to the queue it is
		compared against the existing entries, and if it is either
		intersecting or immediately succeeding/preceeding an existing item it
		is merged.

		There is currently no attempt made at avoiding iterating over the
		existing items in determining whether merging is possible or not.

Diff:

Revision 3 (+80 -15)

Show changes

	src/mem/simple_dram.hh
	src/mem/simple_dram.cc

You have a pending review.

Review Board 2.0.15

This change has been marked as submitted.

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Description:

Changeset 9830:58ba238410d5

Changeset 9831:b5aed07974d4

Diff:

Description:

Changeset 9831:b5aed07974d4

Changeset 9834:4c25c3045a75

Diff:

Status: Closed (submitted)