From: Peng Tao <bergwolf@gmail.com>
To: "Myklebust, Trond" <Trond.Myklebust@netapp.com>
Cc: "bharrosh@panasas.com" <bharrosh@panasas.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH RFC 2/3] NFS41: send real write size in layoutget
Date: Thu, 9 Aug 2012 10:24:19 +0800 [thread overview]
Message-ID: <CA+a=Yy5FkO93xjA2VFa7eGP=CEb3QuM+6frL5cTLnwhQHdr5Ag@mail.gmail.com> (raw)
In-Reply-To: <1344451818.8925.27.camel@lade.trondhjem.org>
On Thu, Aug 9, 2012 at 2:50 AM, Myklebust, Trond
<Trond.Myklebust@netapp.com> wrote:
> On Wed, 2012-08-08 at 10:03 +0800, Peng Tao wrote:
>> From: Peng Tao <tao.peng@emc.com>
>>
>> For bufferred write, scan dirty pages to find out longest continuous
>> dirty pages. In this case, also allow layout driver to specify a
>> maximum layoutget size which is useful to avoid busy scanning dirty pages
>> for block layout client.
>
> This is _really_ ugly, and is a source of potential deadlocks if
> multiple threads are scanning+locking pages at the same time.
Multiple threads won't be able to scan into the same region as borders
are protected by page writeback bit.
>
> Why not simplify this by dropping the complicated tests for whether or
> not the pages are dirty? That gets rid of the deadlock-prone lock_page()
> calls, and would enable you to just use radix_tree_next_hole().
>
OK. I will cook a patch to drop the complicated page dirty/writeback
checks and just use radix_tree_next_hole.
--
Thanks,
Tao
next prev parent reply other threads:[~2012-08-09 2:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-08 2:03 [PATCH RFC 0/3] NFS41: optimize layoutget Peng Tao
2012-08-08 2:03 ` [PATCH RFC 1/3] NFS: track direct IO left bytes Peng Tao
2012-08-08 2:03 ` [PATCH RFC 2/3] NFS41: send real write size in layoutget Peng Tao
2012-08-08 18:50 ` Myklebust, Trond
2012-08-09 2:24 ` Peng Tao [this message]
2012-08-12 18:30 ` Boaz Harrosh
2012-08-12 18:40 ` Boaz Harrosh
2012-08-13 6:15 ` Peng Tao
2012-08-13 9:44 ` Peng Tao
2012-08-13 20:13 ` Boaz Harrosh
2012-08-13 20:21 ` Myklebust, Trond
2012-08-08 2:03 ` [PATCH RFC 3/3] NFS41: send real read size in layoutget for DIO Peng Tao
2012-08-08 18:57 ` Myklebust, Trond
2012-08-09 2:30 ` Peng Tao
2012-08-12 17:39 ` Boaz Harrosh
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