diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2008-06-28 08:31:50 +1000 |
|---|---|---|
| committer | Neil Brown <neilb@notabene.brown> | 2008-06-28 08:31:50 +1000 |
| commit | b203886edbcaac3ca427cf4dbcb50b18bdb346fd (patch) | |
| tree | d96cf939fd3a7ab454f61110b91b3a928eb5fe7c /drivers/md | |
| parent | 0cd17fec983b6bca505eecee1af33138687220b6 (diff) | |
md: kill STRIPE_OP_MOD_DMA in raid5 offload
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 (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 8c4e6149dae..60e61d2464b 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -837,15 +837,10 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx, 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_head *sh) 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); |