Received-SPF: pass (google.com: best guess record for domain of linux-ext4-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Paolo Valente <paolo.valente@linaro.org>
Message-Id: <9E95BE27-2167-430F-9C7F-6D4A0E255FF3@linaro.org>
Content-Type: multipart/signed;
        boundary="Apple-Mail=_4DC1C4F9-FFD5-4309-8346-630474A6C16C";
        protocol="application/pgp-signature";
        micalg=pgp-sha256
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.8\))
Subject: Re: CFQ idling kills I/O performance on ext4 with blkio cgroup
 controller
Date:   Wed, 22 May 2019 11:12:55 +0200
In-Reply-To: <f4b11315-144c-c67d-5143-50b5be950ede@csail.mit.edu>
Cc:     linux-fsdevel@vger.kernel.org,
        linux-block <linux-block@vger.kernel.org>,
        linux-ext4@vger.kernel.org, cgroups@vger.kernel.org,
        kernel list <linux-kernel@vger.kernel.org>,
        Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
        jmoyer@redhat.com, Theodore Ts'o <tytso@mit.edu>,
        amakhalov@vmware.com, anishs@vmware.com, srivatsab@vmware.com
To:     "Srivatsa S. Bhat" <srivatsa@csail.mit.edu>
References: <8d72fcf7-bbb4-2965-1a06-e9fc177a8938@csail.mit.edu>
 <1812E450-14EF-4D5A-8F31-668499E13652@linaro.org>
 <46c6a4be-f567-3621-2e16-0e341762b828@csail.mit.edu>
 <07D11833-8285-49C2-943D-E4C1D23E8859@linaro.org>
 <A0DFE635-EFEC-4670-AD70-5D813E170BEE@linaro.org>
 <5B6570A2-541A-4CF8-98E0-979EA6E3717D@linaro.org>
 <2CB39B34-21EE-4A95-A073-8633CF2D187C@linaro.org>
 <FC24E25F-4578-454D-AE2B-8D8D352478D8@linaro.org>
 <0e3fdf31-70d9-26eb-7b42-2795d4b03722@csail.mit.edu>
 <F5E29C98-6CC4-43B8-994D-0B5354EECBF3@linaro.org>
 <f4b11315-144c-c67d-5143-50b5be950ede@csail.mit.edu>
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk


--Apple-Mail=_4DC1C4F9-FFD5-4309-8346-630474A6C16C
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii


> Il giorno 22 mag 2019, alle ore 11:02, Srivatsa S. Bhat =
<srivatsa@csail.mit.edu> ha scritto:
>=20
> On 5/22/19 1:05 AM, Paolo Valente wrote:
>>=20
>>=20
>>> Il giorno 22 mag 2019, alle ore 00:51, Srivatsa S. Bhat =
<srivatsa@csail.mit.edu> ha scritto:
>>>=20
>>> [ Resending this mail with a dropbox link to the traces (instead
>>> of a file attachment), since it didn't go through the last time. ]
>>>=20
>>> On 5/21/19 10:38 AM, Paolo Valente wrote:
>>>>=20
>>>>> So, instead of only sending me a trace, could you please:
>>>>> 1) apply this new patch on top of the one I attached in my =
previous email
>>>>> 2) repeat your test and report results
>>>>=20
>>>> One last thing (I swear!): as you can see from my script, I tested =
the
>>>> case low_latency=3D0 so far.  So please, for the moment, do your =
test
>>>> with low_latency=3D0.  You find the whole path to this parameter =
in,
>>>> e.g., my script.
>>>>=20
>>> No problem! :) Thank you for sharing patches for me to test!
>>>=20
>>> I have good news :) Your patch improves the throughput significantly
>>> when low_latency =3D 0.
>>>=20
>>> Without any patch:
>>>=20
>>> dd if=3D/dev/zero of=3D/root/test.img bs=3D512 count=3D10000 =
oflag=3Ddsync
>>> 10000+0 records in
>>> 10000+0 records out
>>> 5120000 bytes (5.1 MB, 4.9 MiB) copied, 58.0915 s, 88.1 kB/s
>>>=20
>>>=20
>>> With both patches applied:
>>>=20
>>> dd if=3D/dev/zero of=3D/root/test0.img bs=3D512 count=3D10000 =
oflag=3Ddsync
>>> 10000+0 records in
>>> 10000+0 records out
>>> 5120000 bytes (5.1 MB, 4.9 MiB) copied, 3.87487 s, 1.3 MB/s
>>>=20
>>> The performance is still not as good as mq-deadline (which achieves
>>> 1.6 MB/s), but this is a huge improvement for BFQ nonetheless!
>>>=20
>>> A tarball with the trace output from the 2 scenarios you requested,
>>> one with only the debug patch applied =
(trace-bfq-add-logs-and-BUG_ONs),
>>> and another with both patches applied (trace-bfq-boost-injection) is
>>> available here:
>>>=20
>>> https://www.dropbox.com/s/pdf07vi7afido7e/bfq-traces.tar.gz?dl=3D0
>>>=20
>>=20
>> Hi Srivatsa,
>> I've seen the bugzilla you've created.  I'm a little confused on how
>> to better proceed.  Shall we move this discussion to the bugzilla, or
>> should we continue this discussion here, where it has started, and
>> then update the bugzilla?
>>=20
>=20
> Let's continue here on LKML itself.

Just done :)

> The only reason I created the
> bugzilla entry is to attach the tarball of the traces, assuming
> that it would allow me to upload a 20 MB file (since email attachment
> didn't work). But bugzilla's file restriction is much smaller than
> that, so it didn't work out either, and I resorted to using dropbox.
> So we don't need the bugzilla entry anymore; I might as well close it
> to avoid confusion.
>=20

No no, don't close it: it can reach people that don't use LKML.  We
just have to remember to report back at the end of this.  BTW, I also
think that the bug is incorrectly filed against 5.1, while all these
tests and results concern 5.2-rcX.

Thanks,
Paolo

> Regards,
> Srivatsa
> VMware Photon OS


--Apple-Mail=_4DC1C4F9-FFD5-4309-8346-630474A6C16C
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
	filename=signature.asc
Content-Type: application/pgp-signature;
	name=signature.asc
Content-Description: Message signed with OpenPGP

-----BEGIN PGP SIGNATURE-----
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=EX0B
-----END PGP SIGNATURE-----

--Apple-Mail=_4DC1C4F9-FFD5-4309-8346-630474A6C16C--