From: Paolo Bonzini <pbonzini@redhat.com>
To: liu ping fan <qemulist@gmail.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Avi Kivity <avi@redhat.com>,
Anthony Liguori <anthony@codemonkey.ws>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [big lock] Discussion about the convention of device's DMA each other after breaking down biglock
Date: Thu, 20 Sep 2012 09:54:44 +0200 [thread overview]
Message-ID: <505ACBC4.3030903@redhat.com> (raw)
In-Reply-To: <CAJnKYQnqi+QyqiP6029F_yPDS5kbr1pOhDEGKkH+_8SHUOjLfg@mail.gmail.com>
Il 20/09/2012 09:51, liu ping fan ha scritto:
> Sorry, donot catching your meaning. Does not "coarse->fine" mean
> LOCK(coarse)-->LOCK(fine); .. UNLOCK(fine)-->UNLOCK(coarse) ?
Yes.
>> > Valid:
>> > lock(coarse)
>> > lock(fine)
>> >
> But it is conflict with " localLock(fine) --> bigLock(coarse)" which
> is taken when mmio dispatch.
No, MMIO dispatch has to discard the fine-grained lock before acquiring
the big lock.
If you allow
lock(fine)
lock(coarse)
then the (presumably higher-priority) thread that is requesting the
fine-grained lock must wait for the lower-priority thread that holds the
coarse-grained lock. Then you get priority inversion.
Paolo
next prev parent reply other threads:[~2012-09-20 7:55 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-19 3:02 [Qemu-devel] [big lock] Discussion about the convention of device's DMA each other after breaking down biglock liu ping fan
2012-09-19 8:06 ` Avi Kivity
2012-09-19 9:00 ` liu ping fan
2012-09-19 9:07 ` Avi Kivity
2012-09-19 9:11 ` liu ping fan
2012-09-19 9:14 ` Paolo Bonzini
2012-09-19 9:19 ` liu ping fan
2012-09-19 9:23 ` Avi Kivity
2012-09-19 9:27 ` Jan Kiszka
2012-09-19 9:28 ` Jan Kiszka
2012-09-20 7:51 ` liu ping fan
2012-09-20 7:54 ` Paolo Bonzini [this message]
2012-09-20 8:09 ` liu ping fan
2012-09-20 8:27 ` Paolo Bonzini
2012-09-20 9:07 ` Avi Kivity
2012-09-21 7:27 ` liu ping fan
2012-09-21 8:21 ` Paolo Bonzini
2012-09-19 9:21 ` Avi Kivity
2012-09-19 9:51 ` Paolo Bonzini
2012-09-19 10:06 ` Avi Kivity
2012-09-19 10:19 ` Paolo Bonzini
2012-09-19 10:27 ` Avi Kivity
2012-09-19 9:34 ` Jan Kiszka
2012-09-19 9:50 ` Avi Kivity
2012-09-19 10:18 ` Jan Kiszka
2012-09-24 6:33 ` liu ping fan
2012-09-24 7:44 ` Avi Kivity
2012-09-24 8:32 ` liu ping fan
2012-09-24 9:42 ` Avi Kivity
2012-09-27 3:13 ` liu ping fan
2012-09-27 9:16 ` Avi Kivity
2012-09-27 9:29 ` Paolo Bonzini
2012-09-27 9:34 ` Avi Kivity
2012-09-27 9:36 ` Paolo Bonzini
2012-09-27 10:08 ` Avi Kivity
2012-09-27 10:22 ` Paolo Bonzini
2012-09-27 10:48 ` Avi Kivity
2012-09-29 9:20 ` liu ping fan
2012-09-30 8:13 ` Avi Kivity
2012-09-30 8:48 ` liu ping fan
2012-09-30 11:18 ` Avi Kivity
2012-09-30 11:04 ` Blue Swirl
2012-09-30 11:17 ` Avi Kivity
2012-09-30 11:48 ` Blue Swirl
2012-09-20 8:11 ` liu ping fan
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=505ACBC4.3030903@redhat.com \
--to=pbonzini@redhat.com \
--cc=anthony@codemonkey.ws \
--cc=avi@redhat.com \
--cc=jan.kiszka@siemens.com \
--cc=mtosatti@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=qemulist@gmail.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.