From: "Jim Schutt" <jaschut@sandia.gov>
To: Yehuda Sadeh Weinraub <yehuda.sadeh@dreamhost.com>
Cc: Gregory Farnum <gregory.farnum@dreamhost.com>,
"ceph-devel@vger.kernel.org" <ceph-devel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/6] Understanding delays due to throttling under very heavy write load
Date: Mon, 6 Feb 2012 11:20:25 -0700 [thread overview]
Message-ID: <4F3019E9.80607@sandia.gov> (raw)
In-Reply-To: <CAC-hyiEdAd++dQFBjPDutqipQcMXZqh4RdEEyA=v12vs6ueDxA@mail.gmail.com>
On 02/06/2012 10:22 AM, Yehuda Sadeh Weinraub wrote:
> On Mon, Feb 6, 2012 at 8:20 AM, Jim Schutt<jaschut@sandia.gov> wrote:
>>
>> The above suggests to me that the slowdown is a result
>> of requests not getting submitted at the same rate as
>> when things are running well.
>>
>
> Yeah, it really looks like that. My suggestions wouldn't help there.
>
> I do see that when things go well the number of writes per device is
> capped at ~200 writes per second and the throughput per device is
> ~100MB/sec. Is 100MB/sec the expected device throughput?
Pretty much, at least for the outer tracks on a drive. I've seen
~108 MB/s with dd to a block device. Also, I've got 8 drives per
SAS adapter with 6 Gb/s links, so it seems unlikely to me that my
disk subsystem is any sort of significant bottleneck.
-- Jim
next prev parent reply other threads:[~2012-02-06 18:20 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 15:54 [RFC PATCH 0/6] Understanding delays due to throttling under very heavy write load Jim Schutt
2012-02-01 15:54 ` [RFC PATCH 1/6] msgr: print message sequence number and tid when receiving message envelope Jim Schutt
2012-02-01 15:54 ` [RFC PATCH 2/6] common/Throttle: track sleep/wake sequences in Throttle, report them for policy throttler Jim Schutt
2012-02-01 15:54 ` [RFC PATCH 3/6] common/Throttle: throttle in FIFO order Jim Schutt
2012-02-02 17:53 ` Gregory Farnum
2012-02-02 18:31 ` Jim Schutt
2012-02-02 19:01 ` Gregory Farnum
2012-02-01 15:54 ` [RFC PATCH 4/6] common/Throttle: FIFO throttler doesn't need to signal waiters when max changes Jim Schutt
2012-02-01 15:54 ` [RFC PATCH 5/6] common/Throttle: make get() report number of waiters on entry/exit Jim Schutt
2012-02-01 15:54 ` [RFC PATCH 6/6] msg: log Message interactions with throttler Jim Schutt
2012-02-01 22:33 ` [RFC PATCH 0/6] Understanding delays due to throttling under very heavy write load Gregory Farnum
2012-02-02 15:38 ` Jim Schutt
[not found] ` <4F29CDAA.408@sandia.gov>
[not found] ` <CAF3hT9BZEP_FWS=qt8ivA++aDpPGGFzuD_PtMcvDRS2aDEN+hw@mail.gmail.com>
[not found] ` <4F2AABF5.6050803@sandia.gov>
2012-02-02 17:52 ` Gregory Farnum
2012-02-02 19:06 ` [EXTERNAL] " Jim Schutt
2012-02-02 19:15 ` Sage Weil
2012-02-02 19:33 ` Jim Schutt
2012-02-02 19:32 ` Gregory Farnum
2012-02-02 20:22 ` Jim Schutt
2012-02-02 20:31 ` Jim Schutt
2012-02-03 0:28 ` [EXTERNAL] " Gregory Farnum
2012-02-03 16:17 ` Jim Schutt
2012-02-03 17:06 ` Gregory Farnum
2012-02-03 23:33 ` Jim Schutt
[not found] ` <CAC-hyiHSNv_VgLcyVCrJ66HxTGFNBONrmmBddJk5326dLTKgkw@mail.gmail.com>
2012-02-04 0:04 ` Yehuda Sadeh Weinraub
2012-02-06 16:20 ` Jim Schutt
2012-02-06 17:22 ` Yehuda Sadeh Weinraub
2012-02-06 18:20 ` Jim Schutt [this message]
2012-02-06 18:35 ` Gregory Farnum
2012-02-09 20:53 ` Jim Schutt
2012-02-09 22:40 ` sridhar basam
2012-02-09 23:15 ` Jim Schutt
2012-02-10 0:34 ` Tommi Virtanen
2012-02-10 1:26 ` sridhar basam
2012-02-10 15:32 ` [EXTERNAL] " Jim Schutt
2012-02-10 17:13 ` sridhar basam
2012-02-10 23:09 ` Jim Schutt
2012-02-11 0:05 ` sridhar basam
2012-02-13 15:26 ` Jim Schutt
2012-02-03 17:07 ` Sage Weil
2012-02-24 15:38 ` Jim Schutt
2012-02-24 18:31 ` Tommi Virtanen
2012-02-24 18:38 ` Tommi Virtanen
2013-02-21 0:12 ` Sage Weil
2013-02-26 19:16 ` Jim Schutt
2013-02-26 19:36 ` Sage Weil
2013-02-28 19:37 ` Jim Schutt
2013-02-28 21:06 ` Sage Weil
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