From: Miklos Szeredi <miklos@szeredi.hu>
To: a.p.zijlstra@chello.nl
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC] fuse writable mmap design
Date: Thu, 15 Nov 2007 20:37:27 +0100 [thread overview]
Message-ID: <E1IskWl-0000oJ-00@dorka.pomaz.szeredi.hu> (raw)
In-Reply-To: <1195154530.22457.16.camel@lappy> (message from Peter Zijlstra on Thu, 15 Nov 2007 20:22:10 +0100)
> I'm somewhat confused by the complexity. Currently we can already have a
> lot of dirty pages from FUSE (up to the per BDI dirty limit - so
> basically up to the total dirty limit).
>
> How is having them dirty from mmap'ed writes different?
Nope, fuse never had dirty pages. It does normal writes
synchronously, just updating the cache.
The dirty accounting and then the per-bdi throttling basically made it
possible _at_all_ to have a chance at a writepage implementation which
is not deadlocky (so thanks for those ;).
But there's still the throttle_vm_writeout() thing, and the other
places where the kernel is waiting for a write to complete, which just
cannot be done within a constrained time if an unprivileged userspace
process is involved.
Miklos
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next prev parent reply other threads:[~2007-11-15 19:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-15 16:10 Miklos Szeredi
2007-11-15 19:22 ` Peter Zijlstra
2007-11-15 19:37 ` Miklos Szeredi [this message]
2007-11-15 19:42 ` Peter Zijlstra
2007-11-15 19:57 ` Miklos Szeredi
2007-11-15 20:01 ` Peter Zijlstra
2007-11-15 20:11 ` Miklos Szeredi
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