Messages in this thread |  | | | From | Jeff Moyer <> | | Subject | Re: [PATCH] cfq: improve fsync performance for small files | | Date | Thu, 16 Sep 2010 10:34:49 -0400 |
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Corrado Zoccolo <czoccolo@gmail.com> writes:
> Hi Jens, > any comment on this patch, or the problem we are trying to solve?
Bueller? Bueller?
> > On Tue, Jul 20, 2010 at 10:09 PM, Corrado Zoccolo <czoccolo@gmail.com> wrote: >> Fsync performance for small files achieved by cfq on high-end disks is >> lower than what deadline can achieve, due to idling introduced between >> the sync write happening in process context and the journal commit. >> >> Moreover, when competing with a sequential reader, a process writing >> small files and fsync-ing them is starved. >> >> This patch fixes the two problems by: >> - marking journal commits as WRITE_SYNC, so that they get the REQ_NOIDLE >> flag set, >> - force all queues that have REQ_NOIDLE requests to be put in the noidle >> tree. >> >> Having the queue associated to the fsync-ing process and the one associated >> to journal commits in the noidle tree allows: >> - switching between them without idling, >> - fairness vs. competing idling queues, since they will be serviced only >> after the noidle tree expires its slice. >> >> Acked-by: Vivek Goyal <vgoyal@redhat.com> >> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> >> Tested-by: Jeff Moyer <jmoyer@redhat.com> >> Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com> >> --- >> block/cfq-iosched.c | 18 ++++-------------- >> fs/jbd/commit.c | 2 +- >> fs/jbd2/commit.c | 2 +- >> 3 files changed, 6 insertions(+), 16 deletions(-) >> >> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c >> index eb4086f..49dada4 100644 >> --- a/block/cfq-iosched.c >> +++ b/block/cfq-iosched.c >> @@ -216,7 +216,6 @@ struct cfq_data { >> enum wl_type_t serving_type; >> unsigned long workload_expires; >> struct cfq_group *serving_group; >> - bool noidle_tree_requires_idle; >> >> /* >> * Each priority tree is sorted by next_request position. These >> @@ -2126,7 +2125,6 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) >> slice = max_t(unsigned, slice, CFQ_MIN_TT); >> cfq_log(cfqd, "workload slice:%d", slice); >> cfqd->workload_expires = jiffies + slice; >> - cfqd->noidle_tree_requires_idle = false; >> } >> >> static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) >> @@ -3108,7 +3106,9 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, >> if (cfqq->queued[0] + cfqq->queued[1] >= 4) >> cfq_mark_cfqq_deep(cfqq); >> >> - if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || >> + if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) >> + enable_idle = 0; >> + else if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle || >> (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) >> enable_idle = 0; >> else if (sample_valid(cic->ttime_samples)) { >> @@ -3421,17 +3421,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq) >> cfq_slice_expired(cfqd, 1); >> else if (sync && cfqq_empty && >> !cfq_close_cooperator(cfqd, cfqq)) { >> - cfqd->noidle_tree_requires_idle |= >> - !(rq->cmd_flags & REQ_NOIDLE); >> - /* >> - * Idling is enabled for SYNC_WORKLOAD. >> - * SYNC_NOIDLE_WORKLOAD idles at the end of the tree >> - * only if we processed at least one !REQ_NOIDLE request >> - */ >> - if (cfqd->serving_type == SYNC_WORKLOAD >> - || cfqd->noidle_tree_requires_idle >> - || cfqq->cfqg->nr_cfqq == 1) >> - cfq_arm_slice_timer(cfqd); >> + cfq_arm_slice_timer(cfqd); >> } >> } >> >> diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c >> index 28a9dda..d97a0c6 100644 >> --- a/fs/jbd/commit.c >> +++ b/fs/jbd/commit.c >> @@ -317,7 +317,7 @@ void journal_commit_transaction(journal_t *journal) >> int first_tag = 0; >> int tag_flag; >> int i; >> - int write_op = WRITE; >> + int write_op = WRITE_SYNC; >> >> /* >> * First job: lock down the current transaction and wait for >> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c >> index 75716d3..a078744 100644 >> --- a/fs/jbd2/commit.c >> +++ b/fs/jbd2/commit.c >> @@ -369,7 +369,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) >> int tag_bytes = journal_tag_bytes(journal); >> struct buffer_head *cbh = NULL; /* For transactional checksums */ >> __u32 crc32_sum = ~0; >> - int write_op = WRITE; >> + int write_op = WRITE_SYNC; >> >> /* >> * First job: lock down the current transaction and wait for >> -- >> 1.6.2.5 >> >> >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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