From: Trond Myklebust <trondmy@primarydata.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes
Date: Wed, 15 Jun 2016 15:09:23 +0000 [thread overview]
Message-ID: <02DCF6B5-AFDF-4E33-A8F2-DBFE67A87E91@primarydata.com> (raw)
In-Reply-To: <20160615145638.GC5297@infradead.org>
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On 6/15/16, 10:56, "Christoph Hellwig" <hch@infradead.org> wrote:
>On Wed, Jun 15, 2016 at 02:52:24PM +0000, Trond Myklebust wrote:
>> >But XFS allows full parallelism for direct reads and writes as long
>> >as there is no more pagecache to flush. But if you have pages in
>> >the pagecache you need the exclusive lock to prevent against new
>> >pagecache pages being added.
>>
>> Exactly. So does this.
>
>So let's avoid bloating the inode with another rw_semaphore, and make
>everyones life easier by using the existing lock.
As I said earlier, the problem with that is you end up artificially serialising buffered reads and buffered writes.
• The reads only need a shared lock in order to protect the I/O mode from flipping to O_DIRECT (and relying on page locks to protect against buffered writes).
• The writes need protection against O_DIRECT, they don’t need serialisation with other reads, but they do need to be serialised against other buffered writes.
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WARNING: multiple messages have this Message-ID (diff)
From: Trond Myklebust <trondmy@primarydata.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes
Date: Wed, 15 Jun 2016 15:09:23 +0000 [thread overview]
Message-ID: <02DCF6B5-AFDF-4E33-A8F2-DBFE67A87E91@primarydata.com> (raw)
In-Reply-To: <20160615145638.GC5297@infradead.org>
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next prev parent reply other threads:[~2016-06-15 15:09 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 19:05 [PATCH 01/12] NFS: Don't flush caches for a getattr that races with writeback Trond Myklebust
2016-06-14 19:05 ` [PATCH 02/12] NFS: Cache access checks more aggressively Trond Myklebust
2016-06-14 19:05 ` [PATCH 03/12] NFS: Cache aggressively when file is open for writing Trond Myklebust
2016-06-14 19:05 ` [PATCH 04/12] NFS: Kill NFS_INO_NFS_INO_FLUSHING: it is a performance killer Trond Myklebust
2016-06-14 19:05 ` [PATCH 05/12] NFS: writepage of a single page should not be synchronous Trond Myklebust
2016-06-14 19:05 ` [PATCH 06/12] NFS: Don't hold the inode lock across fsync() Trond Myklebust
2016-06-14 19:05 ` [PATCH 07/12] NFS: Don't enable deep stack recursion when doing memory reclaim Trond Myklebust
2016-06-14 19:05 ` [PATCH 08/12] NFS: Fix O_DIRECT verifier problems Trond Myklebust
2016-06-14 19:05 ` [PATCH 09/12] NFS: Ensure we reset the write verifier 'committed' value on resend Trond Myklebust
2016-06-14 19:05 ` [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes Trond Myklebust
2016-06-14 19:05 ` [PATCH 11/12] NFS: Don't count O_DIRECT reads in the inode->i_dio_count Trond Myklebust
2016-06-14 19:05 ` [PATCH 12/12] NFS: Clean up nfs_direct_complete() Trond Myklebust
2016-06-15 7:16 ` [PATCH 11/12] NFS: Don't count O_DIRECT reads in the inode->i_dio_count Christoph Hellwig
2016-06-15 14:36 ` Trond Myklebust
2016-06-15 14:41 ` Christoph Hellwig
2016-06-15 14:50 ` Trond Myklebust
2016-06-15 14:53 ` Christoph Hellwig
2016-06-15 7:13 ` [PATCH 10/12] NFS: Do not serialise O_DIRECT reads and writes Christoph Hellwig
2016-06-15 14:29 ` Trond Myklebust
2016-06-15 14:48 ` Christoph Hellwig
2016-06-15 14:48 ` Christoph Hellwig
2016-06-15 14:52 ` Trond Myklebust
2016-06-15 14:52 ` Trond Myklebust
2016-06-15 14:56 ` Christoph Hellwig
2016-06-15 14:56 ` Christoph Hellwig
2016-06-15 15:09 ` Trond Myklebust [this message]
2016-06-15 15:09 ` Trond Myklebust
2016-06-15 15:14 ` Christoph Hellwig
2016-06-15 15:14 ` Christoph Hellwig
2016-06-15 15:45 ` Trond Myklebust
2016-06-15 15:45 ` Trond Myklebust
2016-06-16 9:12 ` Christoph Hellwig
2016-06-16 9:12 ` Christoph Hellwig
2016-06-15 7:09 ` [PATCH 07/12] NFS: Don't enable deep stack recursion when doing memory reclaim Christoph Hellwig
2016-06-15 7:08 ` [PATCH 06/12] NFS: Don't hold the inode lock across fsync() Christoph Hellwig
2016-06-15 14:47 ` Trond Myklebust
2016-06-15 14:54 ` Christoph Hellwig
2016-06-17 1:11 ` [PATCH 03/12] NFS: Cache aggressively when file is open for writing Oleg Drokin
2016-06-17 14:01 ` Trond Myklebust
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