From: Chris Mason <chris.mason@oracle.com>
To: Zach Brown <zach.brown@oracle.com>
Cc: Andrew Morton <akpm@osdl.org>, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 0/2] O_DIRECT locking rework
Date: Fri, 20 Oct 2006 16:12:45 -0400 [thread overview]
Message-ID: <20061020201245.GE8674@think.oraclecorp.com> (raw)
In-Reply-To: <45392B8C.3070208@oracle.com>
On Fri, Oct 20, 2006 at 01:03:24PM -0700, Zach Brown wrote:
>
> > I think the fake placeholder page can be a kernel-wide thing rather than
> > per-dio? That would be most desirable because then we have
> >
> > #define PagePlaceHolder(page) (page == global_placeholder_page)
>
> That would be nice. The current patch hashes the page pointer with
> page_waitqueue(page) to get at the zone's hashed wait queue buckets. It
> would probably want to avoid that hot spot by getting at the buckets by
> hashing the mapping and file offset, I guess.
The page_waitqueue part only happens in the contention case. This will
either be buffered vs direct io, direct io vs direct io or direct io vs
truncate. I think all three should be rare enough that a single
waitqueue won't hurt.
It is also very hard to know the file offset without asking the radix
tree, since we can't trust placeholder_page->index.
-chris
next prev parent reply other threads:[~2006-10-20 20:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-20 18:32 [RFC PATCH 0/2] O_DIRECT locking rework Chris Mason
2006-10-20 18:38 ` [RFC PATCH 1/2] placeholder pages Chris Mason
2006-10-20 18:41 ` [RFC PATCH 1/2] page cache locking for O_DIRECT Chris Mason
2006-10-20 19:30 ` [RFC PATCH 0/2] O_DIRECT locking rework Andrew Morton
2006-10-20 20:03 ` Zach Brown
2006-10-20 20:12 ` Chris Mason [this message]
2006-10-20 20:05 ` Chris Mason
2006-10-20 20:23 ` Andi Kleen
2006-10-24 19:34 ` Chris Mason
2006-10-24 19:38 ` [RFC PATCH 1/2] placeholder pages Chris Mason
2006-10-24 19:40 ` [RFC PATCH 2/2] O_DIRECT locking via placeholders Chris Mason
2006-10-24 20:28 ` [RFC PATCH 0/2] O_DIRECT locking rework Badari Pulavarty
2006-10-24 20:50 ` Chris Mason
2006-10-24 21:52 ` Badari Pulavarty
2006-10-24 22:22 ` Chris Mason
2006-10-24 22:47 ` Badari Pulavarty
2006-10-24 22:37 ` Russell Cattelan
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