lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Sat, 28 Mar 2009 11:48:03 +0100
From:	Peter Zijlstra <>
To:	Brice Goglin <>
Cc:	Eric Anholt <>, Andi Kleen <>,,,
	Nick Piggin <>
Subject: Re: DRM lock ordering fix series

On Sat, 2009-03-28 at 09:46 +0100, Brice Goglin wrote:
> Peter Zijlstra wrote:
> > Also note that doing large gup() with gup_fast() will be undesirable due
> > to it disabling IRQs. So iterating say several MB worth of pages will
> > hurt like crazy. Currently all gup_fast() users do a single page lookup.
> >   
> In 2.6.29, fs/bio.c:955, fs/direct-io.c:153 and fs/splice.c:1222 do
> multiple-pages lookup at once. The latter might be limited to 16 pages
> because of the pipe-depth, I don't know about the formers.
> Is there some sort of reasonable limit? A couple dozens pages at once maybe?

Depends on your latency requirements, looking at the code I'd say we'd
have to add that batch limit the comment talks about. I'd see preempt-rt
wanting to lower that significantly.

Regular mainline could do with 32-64 I guess, max irq latency is well
over 10ms on mainline anyway.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists