For a full stripe write, the ideal operation order is handle_stripe_dirtying(),
raid_run_ops(), set R5_Wantwrite bit, and ops_run_io(). In this way, one
handle_stripe() will dispatch IO for the stripe, otherwise there are more extra
rounds of handle_stripe(). In a high speed raid5 array, handle_stripe()
consumes considered cpu time. Reducing its overhead has around 10% performance
boost.
This patch makes handle_stripe() operations follow the ideal order. It also
moves handle_stripe_clean_event() up, as it handles completed stripe. And if I
don't change handle_stripe_clean_event() order, I saw some states confused with
other changes.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
drivers/md/raid5.c | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
Index: linux/drivers/md/raid5.c
===================================================================
--- linux.orig/drivers/md/raid5.c 2014-05-06 17:19:13.868225752 +0800
+++ linux/drivers/md/raid5.c 2014-05-06 17:20:25.367326852 +0800
@@ -1633,7 +1633,7 @@ static void ops_run_check_pq(struct stri
&sh->ops.zero_sum_result, percpu->spare_page, &submit);
}
-static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
+static void raid_run_ops(struct stripe_head *sh, unsigned long *ops_request)
{
int overlap_clear = 0, i, disks = sh->disks;
struct dma_async_tx_descriptor *tx = NULL;
@@ -1644,12 +1644,12 @@ static void raid_run_ops(struct stripe_h
cpu = get_cpu();
percpu = per_cpu_ptr(conf->percpu, cpu);
- if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
+ if (test_and_clear_bit(STRIPE_OP_BIOFILL, ops_request)) {
ops_run_biofill(sh);
overlap_clear++;
}
- if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
+ if (test_and_clear_bit(STRIPE_OP_COMPUTE_BLK, ops_request)) {
if (level < 6)
tx = ops_run_compute5(sh, percpu);
else {
@@ -1659,26 +1659,26 @@ static void raid_run_ops(struct stripe_h
tx = ops_run_compute6_2(sh, percpu);
}
/* terminate the chain if reconstruct is not set to be run */
- if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
+ if (tx && !test_and_clear_bit(STRIPE_OP_RECONSTRUCT, ops_request))
async_tx_ack(tx);
}
- if (test_bit(STRIPE_OP_PREXOR, &ops_request))
+ if (test_and_clear_bit(STRIPE_OP_PREXOR, ops_request))
tx = ops_run_prexor(sh, percpu, tx);
- if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
+ if (test_and_clear_bit(STRIPE_OP_BIODRAIN, ops_request)) {
tx = ops_run_biodrain(sh, tx);
overlap_clear++;
}
- if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
+ if (test_and_clear_bit(STRIPE_OP_RECONSTRUCT, ops_request)) {
if (level < 6)
ops_run_reconstruct5(sh, percpu, tx);
else
ops_run_reconstruct6(sh, percpu, tx);
}
- if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
+ if (test_and_clear_bit(STRIPE_OP_CHECK, ops_request)) {
if (sh->check_state == check_state_run)
ops_run_check_p(sh, percpu);
else if (sh->check_state == check_state_run_q)
@@ -3780,6 +3780,41 @@ static void handle_stripe(struct stripe_
handle_failed_sync(conf, sh, &s);
}
+ /*
+ * might be able to return some write requests if the parity blocks
+ * are safe, or on a failed drive
+ */
+ pdev = &sh->dev[sh->pd_idx];
+ s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
+ || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
+ qdev = &sh->dev[sh->qd_idx];
+ s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
+ || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
+ || conf->level < 6;
+
+ if (s.written &&
+ (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
+ && !test_bit(R5_LOCKED, &pdev->flags)
+ && (test_bit(R5_UPTODATE, &pdev->flags) ||
+ test_bit(R5_Discard, &pdev->flags))))) &&
+ (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
+ && !test_bit(R5_LOCKED, &qdev->flags)
+ && (test_bit(R5_UPTODATE, &qdev->flags) ||
+ test_bit(R5_Discard, &qdev->flags))))))
+ handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
+
+ /* Now to consider new write requests and what else, if anything
+ * should be read. We do not handle new writes when:
+ * 1/ A 'write' operation (copy+xor) is already in flight.
+ * 2/ A 'check' operation is in flight, as it may clobber the parity
+ * block.
+ */
+ if (s.to_write && !sh->reconstruct_state && !sh->check_state)
+ handle_stripe_dirtying(conf, sh, &s, disks);
+
+ if (s.ops_request)
+ raid_run_ops(sh, &s.ops_request);
+
/* Now we check to see if any write operations have recently
* completed
*/
@@ -3817,29 +3852,6 @@ static void handle_stripe(struct stripe_
s.dec_preread_active = 1;
}
- /*
- * might be able to return some write requests if the parity blocks
- * are safe, or on a failed drive
- */
- pdev = &sh->dev[sh->pd_idx];
- s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
- || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
- qdev = &sh->dev[sh->qd_idx];
- s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
- || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
- || conf->level < 6;
-
- if (s.written &&
- (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
- && !test_bit(R5_LOCKED, &pdev->flags)
- && (test_bit(R5_UPTODATE, &pdev->flags) ||
- test_bit(R5_Discard, &pdev->flags))))) &&
- (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
- && !test_bit(R5_LOCKED, &qdev->flags)
- && (test_bit(R5_UPTODATE, &qdev->flags) ||
- test_bit(R5_Discard, &qdev->flags))))))
- handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
-
/* Now we might consider reading some blocks, either to check/generate
* parity, or to satisfy requests
* or to load a block that is being partially written.
@@ -3851,15 +3863,6 @@ static void handle_stripe(struct stripe_
|| s.expanding)
handle_stripe_fill(sh, &s, disks);
- /* Now to consider new write requests and what else, if anything
- * should be read. We do not handle new writes when:
- * 1/ A 'write' operation (copy+xor) is already in flight.
- * 2/ A 'check' operation is in flight, as it may clobber the parity
- * block.
- */
- if (s.to_write && !sh->reconstruct_state && !sh->check_state)
- handle_stripe_dirtying(conf, sh, &s, disks);
-
/* maybe we need to check and possibly fix the parity for this stripe
* Any reads will already have been scheduled, so we just see if enough
* data is available. The parity check is held off while parity
@@ -4014,7 +4017,7 @@ finish:
}
if (s.ops_request)
- raid_run_ops(sh, s.ops_request);
+ raid_run_ops(sh, &s.ops_request);
ops_run_io(sh, &s);
--
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