From: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
To: Hugh Dickins <hugh-DTz5qymZ9yRBDgjK7y7TUQ@public.gmane.org>
Cc: Nick Piggin <npiggin-l3A5Bk7waGM@public.gmane.org>,
Linus Torvalds
<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linux Memory Management List
<linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>
Subject: Re: [rfc] data race in page table setup/walking?
Date: Wed, 30 Apr 2008 07:37:39 +1000 [thread overview]
Message-ID: <1209505059.18023.193.camel@pasglop> (raw)
In-Reply-To: <Pine.LNX.4.64.0804291333540.22025-popGQ1T0qN76K7/ahGyk6A@public.gmane.org>
On Tue, 2008-04-29 at 13:36 +0100, Hugh Dickins wrote:
>
> Ugh. It's just so irritating to introduce these blockages against
> such a remote possibility (but there again, that's what so much of
> kernel code has to be about). Is there any other way of handling it?
Not that much overhead... I think smp_read_barrier_depends() is a nop on
most archs no ? The data dependency between all the pointers takes care
of ordering in many cases. So it boils down to smp_wmb's when setting
which is not that expensive.
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <npiggin@suse.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-arch@vger.kernel.org,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [rfc] data race in page table setup/walking?
Date: Wed, 30 Apr 2008 07:37:39 +1000 [thread overview]
Message-ID: <1209505059.18023.193.camel@pasglop> (raw)
Message-ID: <20080429213739.kRUOkpL3C3ASbJr2zcujJGmwsMq3x4PxckQcSsIx0_0@z> (raw)
In-Reply-To: <Pine.LNX.4.64.0804291333540.22025@blonde.site>
On Tue, 2008-04-29 at 13:36 +0100, Hugh Dickins wrote:
>
> Ugh. It's just so irritating to introduce these blockages against
> such a remote possibility (but there again, that's what so much of
> kernel code has to be about). Is there any other way of handling it?
Not that much overhead... I think smp_read_barrier_depends() is a nop on
most archs no ? The data dependency between all the pointers takes care
of ordering in many cases. So it boils down to smp_wmb's when setting
which is not that expensive.
Cheers,
Ben.
next prev parent reply other threads:[~2008-04-29 21:37 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-29 5:00 [rfc] data race in page table setup/walking? Nick Piggin
2008-04-29 5:00 ` Nick Piggin
[not found] ` <20080429050054.GC21795-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2008-04-29 5:08 ` Benjamin Herrenschmidt
2008-04-29 5:08 ` Benjamin Herrenschmidt
2008-04-29 5:41 ` Nick Piggin
2008-04-29 5:41 ` Nick Piggin
2008-04-29 10:56 ` David Miller
2008-04-29 10:56 ` David Miller
2008-04-29 12:36 ` Hugh Dickins
2008-04-29 12:36 ` Hugh Dickins
[not found] ` <Pine.LNX.4.64.0804291333540.22025-popGQ1T0qN76K7/ahGyk6A@public.gmane.org>
2008-04-29 21:37 ` Benjamin Herrenschmidt [this message]
2008-04-29 21:37 ` Benjamin Herrenschmidt
2008-04-29 22:47 ` Hugh Dickins
2008-04-29 22:47 ` Hugh Dickins
[not found] ` <Pine.LNX.4.64.0804292328110.23470-popGQ1T0qN76K7/ahGyk6A@public.gmane.org>
2008-04-30 0:09 ` Benjamin Herrenschmidt
2008-04-30 0:09 ` Benjamin Herrenschmidt
2008-04-30 6:03 ` Nick Piggin
2008-04-30 6:03 ` Nick Piggin
[not found] ` <20080430060340.GE27652-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2008-04-30 6:05 ` David Miller
2008-04-30 6:05 ` David Miller
[not found] ` <20080429.230543.98200575.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-04-30 6:17 ` Nick Piggin
2008-04-30 6:17 ` Nick Piggin
2008-04-30 11:14 ` Hugh Dickins
2008-04-30 11:14 ` Hugh Dickins
[not found] ` <Pine.LNX.4.64.0804301140490.4651-popGQ1T0qN76K7/ahGyk6A@public.gmane.org>
2008-05-01 0:35 ` Nick Piggin
2008-05-01 0:35 ` Nick Piggin
[not found] ` <20080501003542.GB11312-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2008-05-01 12:45 ` Hugh Dickins
2008-05-01 12:45 ` Hugh Dickins
2008-04-30 15:53 ` Linus Torvalds
2008-04-30 15:53 ` Linus Torvalds
[not found] ` <alpine.LFD.1.10.0804300848390.2997-5CScLwifNT1QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
2008-05-01 0:29 ` Nick Piggin
2008-05-01 0:29 ` Nick Piggin
[not found] ` <20080501002955.GA11312-B4tOwbsTzaBolqkO4TVVkw@public.gmane.org>
2008-05-01 3:24 ` Linus Torvalds
2008-05-01 3:24 ` Linus Torvalds
2008-05-02 1:20 ` Nick Piggin
2008-05-02 1:33 ` Linus Torvalds
2008-05-02 1:43 ` Nick Piggin
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=1209505059.18023.193.camel@pasglop \
--to=benh-xvmvhmargas8u2djnn8i7kb+6bgklq7r@public.gmane.org \
--cc=hugh-DTz5qymZ9yRBDgjK7y7TUQ@public.gmane.org \
--cc=linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org \
--cc=npiggin-l3A5Bk7waGM@public.gmane.org \
--cc=torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
/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