From: Matthew Wilcox <willy@linux.intel.com>
To: Valdis.Kletnieks@vt.edu
Cc: Matthew Wilcox <willy@linux.intel.com>,
Matthew Wilcox <matthew.r.wilcox@intel.com>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 00/21] Add support for NV-DIMMs to ext4
Date: Tue, 30 Sep 2014 12:08:41 -0400 [thread overview]
Message-ID: <20140930160841.GB5098@wil.cx> (raw)
In-Reply-To: <123795.1412088827@turing-police.cc.vt.edu>
On Tue, Sep 30, 2014 at 10:53:47AM -0400, Valdis.Kletnieks@vt.edu wrote:
> On Tue, 30 Sep 2014 10:48:54 -0400, Matthew Wilcox said:
>
> > No, it doesn't try to do that. Wouldn't you be better served with an
> > LD_PRELOAD that forces O_DIRECT on?
>
> Not when you don't want it on every file, and users are creating and
> deleting files once in a while. A chattr-like command is easier and
> more scalable than rebuilding the LD_PRELOAD every time the list of
> files gets changed....
The more I think about this, the more I think this is a bad idea.
When you have a file open with O_DIRECT, your I/O has to be done in
512-byte multiples, and it has to be aligned to 512-byte boundaries
in memory. If an unsuspecting application has O_DIRECT forced on it,
it isn't going to know to do that, and so all its I/Os will fail.
It'll also be horribly inefficient if a program has the file mmaped.
What problem are you really trying to solve? Some big files hogging
the page cache?
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next prev parent reply other threads:[~2014-09-30 16:08 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-25 20:33 [PATCH v11 00/21] Add support for NV-DIMMs to ext4 Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 01/21] axonram: Fix bug in direct_access Matthew Wilcox
2014-10-16 7:52 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 02/21] block: Change direct_access calling convention Matthew Wilcox
2014-10-16 8:45 ` Mathieu Desnoyers
2014-10-16 19:39 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 03/21] mm: Fix XIP fault vs truncate race Matthew Wilcox
2014-10-16 8:56 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 04/21] mm: Allow page fault handlers to perform the COW Matthew Wilcox
2014-10-16 9:12 ` Mathieu Desnoyers
2014-10-16 19:48 ` Matthew Wilcox
2014-10-17 15:35 ` Mathieu Desnoyers
2014-10-18 17:22 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 05/21] vfs,ext2: Introduce IS_DAX(inode) Matthew Wilcox
2014-10-16 9:35 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 06/21] vfs: Add copy_to_iter(), copy_from_iter() and iov_iter_zero() Matthew Wilcox
2014-10-16 13:33 ` Mathieu Desnoyers
2014-10-16 13:59 ` Matthew Wilcox
2014-10-16 14:12 ` Mathieu Desnoyers
2014-10-16 22:21 ` Matthew Wilcox
2014-10-17 15:39 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 07/21] dax,ext2: Replace XIP read and write with DAX I/O Matthew Wilcox
2014-10-16 9:50 ` Mathieu Desnoyers
2014-10-16 19:51 ` Matthew Wilcox
2014-10-16 22:33 ` Matthew Wilcox
2014-10-17 15:52 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 08/21] dax,ext2: Replace ext2_clear_xip_target with dax_clear_blocks Matthew Wilcox
2014-10-16 10:05 ` Mathieu Desnoyers
2014-10-16 21:22 ` Matthew Wilcox
2014-10-17 15:45 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 09/21] dax,ext2: Replace the XIP page fault handler with the DAX page fault handler Matthew Wilcox
2014-10-16 10:20 ` Mathieu Desnoyers
2014-10-16 21:29 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 10/21] dax,ext2: Replace xip_truncate_page with dax_truncate_page Matthew Wilcox
2014-10-16 10:28 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 11/21] dax: Replace XIP documentation with DAX documentation Matthew Wilcox
2014-10-16 12:08 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 12/21] vfs: Remove get_xip_mem Matthew Wilcox
2014-10-16 12:14 ` Mathieu Desnoyers
2014-10-16 21:44 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 13/21] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-10-16 12:18 ` Mathieu Desnoyers
2014-10-16 21:45 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 14/21] ext2: Remove ext2_use_xip Matthew Wilcox
2014-10-16 12:20 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 15/21] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-10-16 12:21 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 16/21] vfs,ext2: Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX Matthew Wilcox
2014-10-16 12:26 ` Mathieu Desnoyers
2014-10-16 21:52 ` Matthew Wilcox
2014-09-25 20:33 ` [PATCH v11 17/21] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-10-16 12:29 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 18/21] ext2: Get rid of most mentions of XIP in ext2 Matthew Wilcox
2014-10-16 12:32 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 19/21] dax: Add dax_zero_page_range Matthew Wilcox
2014-10-16 12:38 ` Mathieu Desnoyers
2014-10-16 22:01 ` Matthew Wilcox
2014-10-17 15:49 ` Mathieu Desnoyers
2014-10-18 17:41 ` Matthew Wilcox
2014-10-18 21:16 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 20/21] ext4: Add DAX functionality Matthew Wilcox
2014-10-16 12:56 ` Mathieu Desnoyers
2014-10-16 22:16 ` Matthew Wilcox
2014-10-17 15:42 ` Mathieu Desnoyers
2014-09-25 20:33 ` [PATCH v11 21/21] brd: Rename XIP to DAX Matthew Wilcox
2014-10-16 13:00 ` Mathieu Desnoyers
2015-03-24 18:50 ` Matt Mullins
2015-03-25 3:25 ` Dave Chinner
2015-03-26 17:09 ` Should implementations of ->direct_access be allowed to sleep? Matthew Wilcox
2015-03-26 19:32 ` Dave Chinner
2015-03-29 8:02 ` Boaz Harrosh
2015-03-29 9:13 ` Boaz Harrosh
2014-09-25 20:47 ` [PATCH v11 00/21] Add support for NV-DIMMs to ext4 Matthew Wilcox
2014-09-30 9:45 ` Valdis.Kletnieks
2014-09-30 14:48 ` Matthew Wilcox
2014-09-30 14:53 ` Valdis.Kletnieks
2014-09-30 16:08 ` Matthew Wilcox [this message]
2014-09-30 17:10 ` Zuckerman, Boris
2014-09-30 19:24 ` Matthew Wilcox
2014-09-30 19:31 ` Zuckerman, Boris
2014-09-30 20:37 ` Valdis.Kletnieks
2014-09-30 21:25 ` Andreas Dilger
2014-09-30 21:52 ` Valdis.Kletnieks
2014-10-01 15:45 ` Jeff Moyer
2014-10-01 17:10 ` Valdis.Kletnieks
2014-10-01 17:17 ` Valdis.Kletnieks
2014-10-16 7:39 ` Mathieu Desnoyers
2014-10-16 14:11 ` Matthew Wilcox
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