From: Paolo Bonzini <pbonzini@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 2/2] msync: start async writeout when MS_ASYNC
Date: Thu, 14 Jun 2012 11:02:02 +0200 [thread overview]
Message-ID: <4FD9A88A.8040701@redhat.com> (raw)
In-Reply-To: <20120613142949.734818a8.akpm@linux-foundation.org>
Il 13/06/2012 23:29, Andrew Morton ha scritto:
> > If the application does not want to start I/O, it can simply call msync
> > with flags equal to MS_INVALIDATE. This one remains a no-op, as it should
> > be on a reasonable implementation.
>
> Means that people will find that their msync(MS_ASYNC) call will newly
> start IO. This may well be undesirable for some.
If they knew it was a no-op, and relying on it, they might as well not
have called it at all and save a syscall.
> Also, it hardwires into the kernel behaviour which userspace itself
> could have initiated, with sync_file_range(). ie: reduced flexibility.
No, it hardwires into the kernel behaviour which is mentioned in the
spec. Strictly speaking it is correct that an asynchronous operation
is never done (the two are indistinguishable), but still this patch
improves the fidelity to the specification and in a portable manner.
Paolo
next prev parent reply other threads:[~2012-06-14 9:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-31 20:43 [PATCH 0/2] msync improvements Paolo Bonzini
2012-05-31 20:43 ` [PATCH 1/2] msync: support syncing a small part of the file Paolo Bonzini
2012-06-13 21:26 ` Andrew Morton
2012-06-13 21:51 ` Zan Lynx
2012-06-13 22:08 ` Andrew Morton
2012-06-14 8:57 ` Paolo Bonzini
2012-05-31 20:43 ` [PATCH 2/2] msync: start async writeout when MS_ASYNC Paolo Bonzini
2012-06-13 21:29 ` Andrew Morton
2012-06-14 9:02 ` Paolo Bonzini [this message]
2012-06-14 10:07 ` Andrew Morton
2012-06-14 10:19 ` Paolo Bonzini
2012-06-14 12:24 ` Paolo Bonzini
2012-06-12 15:38 ` [PATCH 0/2] msync improvements Paolo Bonzini
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