Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6;
From:   bugzilla-daemon@kernel.org
To:     linux-ext4@vger.kernel.org
Subject: [Bug 217965] ext4(?) regression since 6.5.0 on sata hdd
Date:   Wed, 11 Oct 2023 07:53:39 +0000
Message-ID: <bug-217965-13602-YEM8MziGb7@https.bugzilla.kernel.org/>
In-Reply-To: <bug-217965-13602@https.bugzilla.kernel.org/>
References: <bug-217965-13602@https.bugzilla.kernel.org/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Auto-Submitted: auto-generated
MIME-Version: 1.0
Precedence: bulk

https://bugzilla.kernel.org/show_bug.cgi?id=3D217965

--- Comment #12 from Ojaswin Mujoo (ojaswin.mujoo@ibm.com) ---
Hey Ivan,=20

so I used the kernel v6.6-rc1 and the same config you provided as well as w=
ell
as mounted an hdd on my VM. Then I followed the steps here build openwrt [1=
].
However, I'm still unable to replicate the 100% cpu utilization in a
kworker/flush thread (I do get .

Since you have the config options enabled and we didn't see them trigger any
warning and the fact that we get back to normal after a few minutes indicat=
es
that its not a lockup/deadlock. We also see that on faster SSD we don't see
this issue so this might even have something to do with a lot of IOs being
queued up on the slower disk causing us to notice the delay. Maybe we are
waiting a lot more on some spinlock that can explain the CPU utilization.

Since I'm unable to replicate it, I'll have to request you for some more in=
fo
to get to the bottom of this. More specifically, can you kindly provide the
following:

For the kernel with this issue:=20

1. Replicate the 100% util in one terminal window.
2. Once the 100% util is hit, in another terminal run the following command:

$ iostat -x /dev/<dev> 2  (run this for 20 to 30 seconds)=20=20
$ perf record -ag sleep 20
$ echo l > /proc/sysrq_trigger
$ uname -a

3. Repeat the above for a kernel where the issue is not seen.=20

Kindly share the sysrq back trace, iostat output, perf.data and the uname
output  for both the runs here so that I can take a closer look at what is
causing the unusual utilization.

[1] https://github.com/openwrt/openwrt#quickstart


Regards,
ojaswin

--=20
You may reply to this email to add a comment.

You are receiving this mail because:
You are watching the assignee of the bug.=