From: Jeff Dike <jdike@addtoit.com>
To: William Stearns <wstearns@pobox.com>
Cc: ML-uml-devel <user-mode-linux-devel@lists.sourceforge.net>
Subject: Re: [uml-devel] Swapping directly to host swap area?
Date: Tue, 27 Jan 2004 23:39:22 -0500 [thread overview]
Message-ID: <200401280439.i0S4dMZw005517@ccure.user-mode-linux.org> (raw)
In-Reply-To: Your message of "Sun, 25 Jan 2004 18:34:12 EST." <Pine.LNX.4.44.0401251827030.2766-100000@sparrow>
wstearns@pobox.com said:
> When a VM needs to swap out, is there some way the UML kernel could
> send that sector directly to the host swap area instead of running its
> own swap?
No, but this isn't the real question.
> In the current setup, the host kernel sees this as a normal
> write to an open file, caching it in the process and so not truly
> freeing up the ram for a bit.
This is, and this could be done by setting O_DIRECT on UML swap devices. That
way, writes go directly (and asynchronously) to the device without landing
in the cache.
With mmap in effect, this can also be done with a MADVISE_DONTNEED on the
relevant pages of the swap file.
Patches cheerfully accepted.
Jeff
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next prev parent reply other threads:[~2004-01-28 4:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-25 23:34 [uml-devel] Swapping directly to host swap area? William Stearns
2004-01-27 3:01 ` Dan Shearer
2004-01-28 4:39 ` Jeff Dike [this message]
2004-01-28 14:01 ` [uml-devel] O_DIRECT (was: Swapping directly to host swap area?) Goetz Bock
2004-01-30 17:27 ` Jeff Dike
2004-02-05 16:59 ` [uml-devel] Swapping directly to host swap area? BlaisorBlade
2004-02-11 0:43 ` Jeff Dike
2004-02-12 19:08 ` BlaisorBlade
2004-02-12 21:36 ` Jeff Dike
2004-03-19 5:51 ` William Stearns
2004-03-19 16:58 ` Matt Ayres
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