From: Shaohua Li <shli@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: "Matias Bjørling" <m@bjorling.me>,
"Sam Bradshaw (sbradshaw)" <sbradshaw@micron.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] block: per-cpu counters for in-flight IO accounting
Date: Thu, 5 Jun 2014 10:09:34 +0800 [thread overview]
Message-ID: <20140605020934.GB13953@kernel.org> (raw)
In-Reply-To: <538F7CCE.3050508@kernel.dk>
On Wed, Jun 04, 2014 at 02:08:46PM -0600, Jens Axboe wrote:
> On 06/04/2014 05:29 AM, Matias Bjørling wrote:
> > It's in
> >
> > blk_io_account_start
> > part_round_stats
> > part_round_state_single
> > part_in_flight
> >
> > I like the granularity idea.
>
> And similarly from blk_io_account_done() - which makes it even worse,
> since it at both ends of the IO chain.
But part_round_state_single is supposed to only call part_in_flight every
jiffery. Maybe we need something below:
1. set part->stamp immediately
2. fixed granularity
Untested though.
diff --git a/block/blk-core.c b/block/blk-core.c
index 40d6548..5f0acaa 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1270,17 +1270,19 @@ static void part_round_stats_single(int cpu, struct hd_struct *part,
unsigned long now)
{
int inflight;
+ unsigned long old_stamp;
- if (now == part->stamp)
+ if (time_before(now, part->stamp + msecs_to_jiffies(10)))
return;
+ old_stamp = part->stamp;
+ part->stamp = now;
inflight = part_in_flight(part);
if (inflight) {
__part_stat_add(cpu, part, time_in_queue,
- inflight * (now - part->stamp));
- __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
+ inflight * (now - old_stamp));
+ __part_stat_add(cpu, part, io_ticks, (now - old_stamp));
}
- part->stamp = now;
}
/**
next prev parent reply other threads:[~2014-06-05 2:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-09 9:17 [PATCH] block: small performance optimization Matias Bjørling
2014-05-09 9:17 ` [PATCH] block: per-cpu counters for in-flight IO accounting Matias Bjørling
2014-05-09 14:12 ` Jens Axboe
2014-05-09 16:41 ` Jens Axboe
2014-05-30 12:11 ` Shaohua Li
2014-05-30 13:49 ` Jens Axboe
2014-06-04 10:39 ` Shaohua Li
2014-06-04 11:29 ` Matias Bjørling
2014-06-04 20:08 ` Jens Axboe
2014-06-05 2:09 ` Shaohua Li [this message]
2014-06-05 2:16 ` Jens Axboe
2014-06-05 2:33 ` Shaohua Li
2014-06-05 2:42 ` Jens Axboe
2014-06-04 14:29 ` Jens Axboe
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