From: Michal Rostecki <mrostecki@suse.de>
To: Anand Jain <anand.jain@oracle.com>
Cc: linux-btrfs@vger.kernel.org, dsterba@suse.com, josef@toxicpanda.com
Subject: Re: [PATCH v3 1/4] btrfs: add read_policy latency
Date: Wed, 20 Jan 2021 13:54:57 +0000 [thread overview]
Message-ID: <20210120135457.GA6831@wotan.suse.de> (raw)
In-Reply-To: <bc5665c0-f066-39af-48e2-dbc063b260ed@oracle.com>
On Wed, Jan 20, 2021 at 08:30:56PM +0800, Anand Jain wrote:
> I ran fio tests again, now with dstat in an another window. I don't
> notice any such stalls, the read numbers went continuous until fio
> finished. Could you please check with the below fio command, also
> could you please share your fio command options.
That's the fio config I used:
https://gitlab.com/vadorovsky/playground/-/blob/master/fio/btrfs-raid1-seqread.fio
The main differences seem to be:
- the number of jobs (I used the number of CPU threads)
- direct vs buffered I/O
>
> fio \
> --filename=/btrfs/largefile \
> --directory=/btrfs \
> --filesize=50G \
> --size=50G \
> --bs=64k \
> --ioengine=libaio \
> --rw=read \
> --direct=1 \
> --numjobs=1 \
> --group_reporting \
> --thread \
> --name iops-test-job
>
> It is system specific?
With this command, dstat output looks good:
https://paste.opensuse.org/view/simple/93159623
So I think it might be specific to whether we test direct of buffered
I/O. Or to the number of jobs (single vs multiple jobs). Since the most
of I/O on production environments is usually buffered, I think we should
test with direct=0 too.
Cheers,
Michal
next prev parent reply other threads:[~2021-01-20 14:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 9:41 [PATCH v3 0/4] btrfs: read_policy types latency, device and round-robin Anand Jain
2021-01-11 9:41 ` [PATCH v3 1/4] btrfs: add read_policy latency Anand Jain
2021-01-19 19:36 ` Josef Bacik
2021-01-20 2:43 ` Anand Jain
2021-01-20 10:27 ` Michal Rostecki
2021-01-20 12:30 ` Anand Jain
2021-01-20 13:54 ` Michal Rostecki [this message]
2021-01-21 10:45 ` Anand Jain
2021-01-11 9:41 ` [PATCH v3 2/4] btrfs: introduce new device-state read_preferred Anand Jain
2021-01-19 19:44 ` Josef Bacik
2021-01-11 9:41 ` [PATCH v3 3/4] btrfs: introduce new read_policy device Anand Jain
2021-01-19 19:44 ` Josef Bacik
2021-01-11 9:41 ` [PATCH RFC 4/4] btrfs: introduce new read_policy round-robin Anand Jain
2021-01-19 19:41 ` Josef Bacik
2021-01-20 2:40 ` Anand Jain
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