From: NeilBrown <neilb@suse.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org,
Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH 019 of 29] md: md: kill STRIPE_OP_MOD_DMA in raid5 offload
Date: Fri, 27 Jun 2008 16:51:23 +1000 [thread overview]
Message-ID: <1080627065123.10617@suse.de> (raw)
In-Reply-To: 20080627164503.9671.patches@notabene
From: Dan Williams <dan.j.williams@intel.com>
This micro-optimization allowed the raid code to skip a re-read of the
parity block after checking parity. It took advantage of the fact that
xor-offload-engines have their own internal result buffer and can check
parity without writing to memory. Remove it for the following reasons:
1/ It is a layering violation for MD to need to manage the DMA and
non-DMA paths within async_xor_zero_sum
2/ Bad precedent to toggle the 'ops' flags outside the lock
3/ Hard to realize a performance gain as reads will not need an updated
parity block and writes will dirty it anyways.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Neil Brown <neilb@suse.de>
### Diffstat output
./drivers/md/raid5.c | 10 ----------
./include/linux/raid/raid5.h | 2 --
2 files changed, 12 deletions(-)
diff .prev/drivers/md/raid5.c ./drivers/md/raid5.c
--- .prev/drivers/md/raid5.c 2008-06-27 16:20:58.000000000 +1000
+++ ./drivers/md/raid5.c 2008-06-27 16:22:03.000000000 +1000
@@ -837,15 +837,10 @@ ops_run_postxor(struct stripe_head *sh,
static void ops_complete_check(void *stripe_head_ref)
{
struct stripe_head *sh = stripe_head_ref;
- int pd_idx = sh->pd_idx;
pr_debug("%s: stripe %llu\n", __func__,
(unsigned long long)sh->sector);
- if (test_and_clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending) &&
- sh->ops.zero_sum_result == 0)
- set_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
-
set_bit(STRIPE_OP_CHECK, &sh->ops.complete);
set_bit(STRIPE_HANDLE, &sh->state);
release_stripe(sh);
@@ -873,11 +868,6 @@ static void ops_run_check(struct stripe_
tx = async_xor_zero_sum(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
&sh->ops.zero_sum_result, 0, NULL, NULL, NULL);
- if (tx)
- set_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
- else
- clear_bit(STRIPE_OP_MOD_DMA_CHECK, &sh->ops.pending);
-
atomic_inc(&sh->count);
tx = async_trigger_callback(ASYNC_TX_DEP_ACK | ASYNC_TX_ACK, tx,
ops_complete_check, sh);
diff .prev/include/linux/raid/raid5.h ./include/linux/raid/raid5.h
--- .prev/include/linux/raid/raid5.h 2008-06-27 16:20:33.000000000 +1000
+++ ./include/linux/raid/raid5.h 2008-06-27 16:22:03.000000000 +1000
@@ -267,10 +267,8 @@ struct r6_state {
/* modifiers to the base operations
* STRIPE_OP_MOD_REPAIR_PD - compute the parity block and write it back
- * STRIPE_OP_MOD_DMA_CHECK - parity is not corrupted by the check
*/
#define STRIPE_OP_MOD_REPAIR_PD 7
-#define STRIPE_OP_MOD_DMA_CHECK 8
/*
* Plugging:
next prev parent reply other threads:[~2008-06-27 6:51 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-27 6:49 [PATCH 000 of 29] md: Introduction : patchbomb for 2.6.27 merge window NeilBrown
2008-06-27 6:49 ` [PATCH 001 of 29] md: Ensure interrupted recovery completed properly (v1 metadata plus bitmap) NeilBrown
2008-07-01 7:20 ` Jan Engelhardt
2008-06-27 6:49 ` [PATCH 002 of 29] md: Don't acknowlege that stripe-expand is complete until it really is NeilBrown
2008-06-27 6:49 ` [PATCH 003 of 29] md: Fix error paths if md_probe fails NeilBrown
2008-06-27 6:49 ` [PATCH 004 of 29] md: linear: correct disk numbering error check NeilBrown
2008-06-27 6:49 ` [PATCH 005 of 29] md: use bio_endio instead of a call to bi_end_io NeilBrown
2008-06-27 6:49 ` [PATCH 006 of 29] md: Improve setting of "events_cleared" for write-intent bitmaps NeilBrown
2008-06-27 6:50 ` [PATCH 007 of 29] md: Allow setting start point for requested check/repair NeilBrown
2008-06-27 6:50 ` [PATCH 008 of 29] md: Close race in md_probe NeilBrown
2008-06-27 12:21 ` Andre Noll
2008-06-27 23:38 ` Neil Brown
2008-06-30 7:52 ` Andre Noll
2008-06-27 6:50 ` [PATCH 009 of 29] md: Don't try to make md arrays dirty if that is not meaningful NeilBrown
2008-06-27 6:50 ` [PATCH 010 of 29] md: Enable setting of 'offset' and 'size' of a hot-added spare NeilBrown
2008-06-27 6:50 ` [PATCH 011 of 29] md: Support adding a spare to a live md array with external metadata NeilBrown
2008-06-27 6:50 ` [PATCH 012 of 29] md: rationalise return value for ->hot_add_disk method NeilBrown
2008-06-27 6:50 ` [PATCH 013 of 29] md: Don't reject HOT_REMOVE_DISK request for an array that is not yet started NeilBrown
2008-06-27 6:50 ` [PATCH 014 of 29] md: Make sure all changes to md/array_state are notified NeilBrown
2008-06-27 6:50 ` [PATCH 015 of 29] md: Make sure all changes to md/sync_action " NeilBrown
2008-06-27 6:51 ` [PATCH 016 of 29] md: Make sure all changes to md/degraded " NeilBrown
2008-06-27 6:51 ` [PATCH 017 of 29] md: Make sure all changes to md/dev-XX/state " NeilBrown
2008-06-27 6:51 ` [PATCH 018 of 29] md: Support changing rdev size on running arrays NeilBrown
2008-06-27 16:09 ` Markus Hochholdinger
2008-06-27 23:41 ` Neil Brown
2010-03-30 14:52 ` Markus Hochholdinger
2010-03-31 5:41 ` Neil Brown
2010-04-01 15:23 ` Markus Hochholdinger
2012-03-24 20:47 ` Markus Hochholdinger
2012-03-25 22:15 ` NeilBrown
2021-11-10 13:09 ` Markus Hochholdinger
2021-11-10 17:51 ` Markus Hochholdinger
2021-11-11 13:10 ` Markus Hochholdinger
2021-11-11 15:09 ` Markus Hochholdinger
2021-11-12 1:22 ` Guoqing Jiang
2021-11-12 14:31 ` Markus Hochholdinger
2008-06-27 6:51 ` NeilBrown [this message]
2008-06-27 6:51 ` [PATCH 020 of 29] md: md: kill STRIPE_OP_IO flag NeilBrown
2008-06-27 6:51 ` [PATCH 021 of 29] md: md: use stripe_head_state in ops_run_io() NeilBrown
2008-06-27 6:51 ` [PATCH 022 of 29] md: md: unify raid5/6 i/o submission NeilBrown
2008-06-27 6:51 ` [PATCH 023 of 29] md: md: replace STRIPE_OP_CHECK with 'check_states' NeilBrown
2008-06-27 6:51 ` [PATCH 024 of 29] md: md: replace STRIPE_OP_BIOFILL with STRIPE_BIOFILL_RUN NeilBrown
2008-06-27 6:52 ` [PATCH 025 of 29] md: md: replace STRIPE_OP_COMPUTE_BLK with STRIPE_COMPUTE_RUN NeilBrown
2008-06-27 6:52 ` [PATCH 026 of 29] md: md: replace STRIPE_OP_{BIODRAIN,PREXOR,POSTXOR} with 'reconstruct_states' NeilBrown
2008-06-27 6:52 ` [PATCH 027 of 29] md: md: replace R5_WantPrexor with R5_WantDrain, add 'prexor' reconstruct_states NeilBrown
2008-06-27 6:52 ` [PATCH 028 of 29] md: md: handle operation chaining in raid5_run_ops NeilBrown
2008-06-27 6:52 ` [PATCH 029 of 29] md: md: rationalize raid5 function names NeilBrown
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