From: Paolo Bonzini <pbonzini@redhat.com>
To: Yunhong Jiang <yunhong.jiang@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC PATCH] VFIO: Add a parameter to force nonthread IRQ
Date: Wed, 28 Oct 2015 19:28:57 +0100 [thread overview]
Message-ID: <563113E9.2040608@redhat.com> (raw)
In-Reply-To: <20151028175013.GA21961@jnakajim-build>
On 28/10/2015 18:50, Yunhong Jiang wrote:
> > No, I don't think you can use raw_spinlock there. The problem is not
> > just eventfd_signal, it is especially wake_up_locked_poll. You cannot
> > convert the whole workqueue infrastructure to use raw_spinlock.
>
> You mean the waitqueue, instead of workqueue, right?
Yes.
> One choice is to change
> the eventfd to use simple wait queue, which is raw_spinlock. But use simple
> waitqueue on eventfd may in fact impact real time latency if not in this
> scenario.
Userspace can put an arbitrary amount of tasks on the work queue, so
it's not possible to use a simple wait queue. It would also touch
multiple subsystems, so it's much better to bypass the eventfd completely.
Paolo
prev parent reply other threads:[~2015-10-28 18:28 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-27 1:20 [RFC PATCH] VFIO: Add a parameter to force nonthread IRQ Yunhong Jiang
2015-10-27 3:37 ` Alex Williamson
2015-10-27 6:35 ` Yunhong Jiang
2015-10-27 9:29 ` Paolo Bonzini
2015-10-27 21:26 ` Yunhong Jiang
2015-10-28 0:44 ` Paolo Bonzini
2015-10-28 16:00 ` Alex Williamson
2015-10-28 17:05 ` Paolo Bonzini
2015-10-28 23:54 ` Marcelo Tosatti
2015-10-29 3:11 ` Alex Williamson
2015-10-29 9:45 ` Paolo Bonzini
2015-10-30 6:16 ` Yunhong Jiang
2015-11-02 9:17 ` Paolo Bonzini
2015-10-28 17:50 ` Yunhong Jiang
2015-10-28 18:18 ` Alex Williamson
2015-10-28 21:46 ` Yunhong Jiang
2015-10-28 18:28 ` Paolo Bonzini [this message]
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=563113E9.2040608@redhat.com \
--to=pbonzini@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=yunhong.jiang@linux.intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.