From: Keith Busch <kbusch@kernel.org>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: bigeasy@linutronix.de, tglx@linutronix.de, hch@lst.de,
linux-nvme@lists.infradead.org, ming.lei@redhat.com
Subject: Re: [PATCHv3 2/4] nvme/pci: Complete commands from primary handler
Date: Thu, 12 Dec 2019 02:35:32 +0900 [thread overview]
Message-ID: <20191211173532.GB493@redsun51.ssa.fujisawa.hgst.com> (raw)
In-Reply-To: <c58e2cb5-e03c-c56f-8c67-a791ac1eb2c6@grimberg.me>
On Tue, Dec 10, 2019 at 01:14:19PM -0800, Sagi Grimberg wrote:
> > > If I have say 24 (or more) devices with a queue mapped to a cpu, and we
> > > happen to just reap in the primary handler for all devices, all the time,
> > > are we safe from cpu lockup?
> >
> > I can't readily test that scenario, but I'm skeptical a workload
> > can keep the primary handler running without ever seeing it return
> > IRQ_WAKE_THREAD. If that is really a problem, we can mitigate it by
> > limiting the number of CQEs the primary handler may process.
>
> Theoretically speaking, even if you limit to 1 cqe, the universe can
> align such that you will always reap in the primary handler right?
Perhaps theoretically, though testing the limits of reason.
> So if we have this optimization, perhaps something else in the irq
> infrastructure should take care of cpu lockup prevention?
Perhaps we can cycle the effective_affinity through the smp_affinity?
_______________________________________________
linux-nvme mailing list
linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme
next prev parent reply other threads:[~2019-12-11 17:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 17:56 [PATCHv3 0/4] nvme pci interrupt handling improvements Keith Busch
2019-12-09 17:56 ` [PATCHv3 1/4] nvme/pci: Disable interrupts for threaded handler Keith Busch
2019-12-10 15:12 ` Daniel Wagner
2019-12-10 15:28 ` Sebastian Andrzej Siewior
2019-12-10 15:54 ` Keith Busch
2019-12-10 16:44 ` Daniel Wagner
2019-12-10 16:57 ` Keith Busch
2019-12-10 17:11 ` Daniel Wagner
2019-12-12 9:09 ` Christoph Hellwig
2019-12-12 15:53 ` Keith Busch
2019-12-09 17:56 ` [PATCHv3 2/4] nvme/pci: Complete commands from primary handler Keith Busch
2019-12-10 20:00 ` Sagi Grimberg
2019-12-10 20:25 ` Keith Busch
2019-12-10 21:14 ` Sagi Grimberg
2019-12-11 17:35 ` Keith Busch [this message]
2019-12-12 0:40 ` Sagi Grimberg
2019-12-12 1:02 ` Keith Busch
2019-12-12 22:55 ` Ming Lei
2019-12-12 23:30 ` Keith Busch
2019-12-13 0:52 ` Ming Lei
2019-12-12 9:14 ` Christoph Hellwig
2019-12-09 17:56 ` [PATCHv3 3/4] nvme/pci: Remove use_threaded_interrupts Keith Busch
2019-12-12 9:14 ` Christoph Hellwig
2019-12-12 15:45 ` Keith Busch
2019-12-18 7:29 ` Ming Lei
2019-12-18 15:50 ` Keith Busch
2019-12-19 1:10 ` Ming Lei
2019-12-09 17:56 ` [PATCHv3 4/4] nvme/pci: Poll threaded completions Keith Busch
2019-12-10 17:43 ` Daniel Wagner
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=20191211173532.GB493@redsun51.ssa.fujisawa.hgst.com \
--to=kbusch@kernel.org \
--cc=bigeasy@linutronix.de \
--cc=hch@lst.de \
--cc=linux-nvme@lists.infradead.org \
--cc=ming.lei@redhat.com \
--cc=sagi@grimberg.me \
--cc=tglx@linutronix.de \
/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).