From: "Elliott, Robert (Persistent Memory)" <elliott@hpe.com>
To: Sreekanth Reddy <sreekanth.reddy@broadcom.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"irqbalance@lists.infradead.org" <irqbalance@lists.infradead.org>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>,
Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>,
Chaitra Basappa <chaitra.basappa@broadcom.com>,
Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Subject: RE: Observing Softlockup's while running heavy IOs
Date: Thu, 18 Aug 2016 21:08:18 +0000 [thread overview]
Message-ID: <DF4PR84MB01696549697831B4CEC4A3FDAB150@DF4PR84MB0169.NAMPRD84.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <CAK=zhgqkByFSYRYcY75+55kP0ysHbgpk1L9=qxAfLdoFfsa6sQ@mail.gmail.com>
> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> owner@vger.kernel.org] On Behalf Of Sreekanth Reddy
> Sent: Thursday, August 18, 2016 12:56 AM
> Subject: Observing Softlockup's while running heavy IOs
>
> Problem statement:
> Observing softlockups while running heavy IOs on 8 SSD drives
> connected behind our LSI SAS 3004 HBA.
>
...
> Observing a loop in the IO path, i.e only one CPU is busy with
> processing the interrupts and other CPUs (in the affinity_hint mask)
> are busy with sending the IOs (these CPUs are not yet all receiving
> any interrupts). For example, only CPU6 is busy with processing the
> interrupts from IRQ 219 and remaining CPUs i.e CPU 7,8,9,10 & 11 are
> just busy with pumping the IOs and they never processed any IO
> interrupts from IRQ 219. So we are observing softlockups due to
> existence this loop in the IO Path.
>
> We may not observe these softlockups if irqbalancer might have
> balanced the interrupts among the CPUs enabled in the particular
> irq's
> affinity_hint mask. so that all the CPUs are equaly busy with send
> IOs
> and processing the interrupts. I am not sure how irqbalancer balance
> the load among the CPUs, but here I see only one CPU from irq's
> affinity_hint mask is busy with interrupts and remaining CPUs won't
> receive any interrupts from this IRQ.
>
> Please help me with any suggestions/recomendations to slove/limit
> these kind of softlockups. Also please let me known if I have missed
> any setting in the irqbalance.
>
The CPUs need to be forced to self-throttle by processing interrupts for
their own submissions, which reduces the time they can submit more IOs.
See https://lkml.org/lkml/2014/9/9/931 for discussion of this
problem when blk-mq was added.
---
Robert Elliott, HPE Persistent Memory
next prev parent reply other threads:[~2016-08-19 1:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-18 5:55 Observing Softlockup's while running heavy IOs Sreekanth Reddy
2016-08-18 14:59 ` Bart Van Assche
2016-08-18 21:08 ` Elliott, Robert (Persistent Memory) [this message]
2016-08-19 11:44 ` Sreekanth Reddy
2016-08-19 15:56 ` Bart Van Assche
2016-09-01 10:31 ` Sreekanth Reddy
2016-09-01 23:04 ` Bart Van Assche
[not found] ` <CAK=zhgrLL22stCfwKdpJkN=PkxPVxL=K9RgpP1USEbg_xx5TEg@mail.gmail.com>
2016-09-06 15:06 ` Neil Horman
2016-09-07 6:00 ` Sreekanth Reddy
2016-09-07 13:24 ` Neil Horman
2016-09-08 5:42 ` Sreekanth Reddy
2016-09-08 13:39 ` Neil Horman
2016-09-12 8:18 ` Sreekanth Reddy
2016-09-12 12:03 ` Neil Horman
2016-08-19 21:27 ` Elliott, Robert (Persistent Memory)
2016-08-23 9:52 ` Kashyap Desai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=DF4PR84MB01696549697831B4CEC4A3FDAB150@DF4PR84MB0169.NAMPRD84.PROD.OUTLOOK.COM \
--to=elliott@hpe.com \
--cc=chaitra.basappa@broadcom.com \
--cc=irqbalance@lists.infradead.org \
--cc=kashyap.desai@broadcom.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=sathya.prakash@broadcom.com \
--cc=sreekanth.reddy@broadcom.com \
--cc=suganath-prabu.subramani@broadcom.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).