On Tue, May 18, 2010 at 02:20:17PM -0400, Jeff Moyer wrote:
> This patch uses an average think time for the entirety of the sync-noidle
> workload to determine whether or not to idle on said workload. This brings
> it more in line with the policy for the sync queues in the sync workload.
>
> Testing shows that this provided an overall increase in throughput for
> a mixed workload on my hardware RAID array.
>
> Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
> ---
> block/cfq-iosched.c | 44 +++++++++++++++++++++++++++++++++++++++-----
> 1 files changed, 39 insertions(+), 5 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 838834b..46a7fe5 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -83,9 +83,14 @@ struct cfq_rb_root {
> unsigned total_weight;
> u64 min_vdisktime;
> struct rb_node *active;
> + unsigned long last_end_request;
> + unsigned long ttime_total;
> + unsigned long ttime_samples;
> + unsigned long ttime_mean;
> };
> #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
> - .count = 0, .min_vdisktime = 0, }
> + .count = 0, .min_vdisktime = 0, .last_end_request = 0, \
> + .ttime_total = 0, .ttime_samples = 0, .ttime_mean = 0 }
>
> /*
> * Per process-grouping structure
> @@ -962,8 +967,10 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
> goto done;
>
> cfqg->weight = blkcg->weight;
> - for_each_cfqg_st(cfqg, i, j, st)
> + for_each_cfqg_st(cfqg, i, j, st) {
> *st = CFQ_RB_ROOT;
> + st->last_end_request = jiffies;
> + }
> RB_CLEAR_NODE(&cfqg->rb_node);
>
> /*
> @@ -1795,9 +1802,12 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>
> /*
> * Otherwise, we do only if they are the last ones
> - * in their service tree.
> + * in their service tree and the average think time is
> + * less than the slice length.
> */
> - if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
> + if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
> + (!sample_valid(service_tree->ttime_samples ||
^^^
Jeff,
Are we closing sample_valid() bracket at right place here?
I am wondering where it is helping you. If it is to bring in line with
with sync tree (old implementation), then we should have also compared
the think time with slice_idle?
But comparing that here might not be the best thing as cfq_should_idle()
is used in many contexts.
Vivek
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