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From: Geoffrey Wehrman <gwehrman@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: Issues with delalloc->real extent allocation
Date: Tue, 18 Jan 2011 08:30:00 -0600	[thread overview]
Message-ID: <20110118143000.GB8803@sgi.com> (raw)
In-Reply-To: <20110118002437.GS28803@dastard>

On Tue, Jan 18, 2011 at 11:24:37AM +1100, Dave Chinner wrote:
| On Mon, Jan 17, 2011 at 08:37:08AM -0600, Geoffrey Wehrman wrote:
| > On Mon, Jan 17, 2011 at 04:18:28PM +1100, Dave Chinner wrote:
| > | However, this does not solve the extsize allocation issues where we
| > | don't have dirty pages in the page cache covering parts of the
| > | delayed allocation extent so we still need a solution for that. I'm
| > | tending towards zeroing in .aio_write as the simplest solution
| > | because it doesn't cause buffer head/extent tree mapping mismatches,
| > | and it would use the above intent/done operations for crash
| > | resilience so there's no additional, rarely used code path to test
| > | through .writepage. Does that sound reasonable?
| > 
| > Zeroing in .aio_write will create zeroed pages covering the entire
| > allocation, correct?
| 
| Yes, though it only needs to zero the regions that the write does
| not cover itself - no need to zero what we're about to put data
| into. ;)

Glad you were able to understand what I meant.  Something I didn't think
of earlier though:  What happens when I try to use an 8 GB on a system
with only 4 GB of memory?  I'm not really worried about this pathological
case, but I do wonder what the effects will be of allocating what could
be significant quantities of memory in .aio_write.


-- 
Geoffrey Wehrman  651-683-5496  gwehrman@sgi.com

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  reply	other threads:[~2011-01-18 14:27 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-14  0:29 Issues with delalloc->real extent allocation Dave Chinner
2011-01-14 16:40 ` Geoffrey Wehrman
2011-01-14 22:59   ` Dave Chinner
2011-01-15  4:16     ` Geoffrey Wehrman
2011-01-17  5:18       ` Dave Chinner
2011-01-17 14:37         ` Geoffrey Wehrman
2011-01-18  0:24           ` Dave Chinner
2011-01-18 14:30             ` Geoffrey Wehrman [this message]
2011-01-18 20:40               ` Christoph Hellwig
2011-01-18 22:03                 ` Dave Chinner
2011-01-14 21:43 ` bpm
2011-01-14 23:32   ` bpm
2011-01-14 23:50   ` bpm
2011-01-14 23:55   ` Dave Chinner
2011-01-17 20:12     ` bpm
2011-01-18  1:44       ` Dave Chinner
2011-01-18 20:47     ` Christoph Hellwig
2011-01-18 23:18       ` Dave Chinner
2011-01-19 12:03         ` Christoph Hellwig
2011-01-19 13:31           ` Dave Chinner
2011-01-19 13:55             ` Christoph Hellwig
2011-01-20  1:33               ` Dave Chinner
2011-01-20 11:16                 ` Christoph Hellwig
2011-01-21  1:59                   ` Dave Chinner
2011-01-20 14:45                 ` Geoffrey Wehrman
2011-01-21  2:51                   ` Dave Chinner
2011-01-21 14:41                     ` Geoffrey Wehrman
2011-01-23 23:26                       ` Dave Chinner
2011-01-17  0:28   ` Lachlan McIlroy
2011-01-17  4:37     ` Dave Chinner

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