From: Valdis.Kletnieks@vt.edu
To: Matthew Wilcox <willy@linux.intel.com>
Cc: 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 16:37:56 -0400 [thread overview]
Message-ID: <15704.1412109476@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Tue, 30 Sep 2014 12:08:41 -0400." <20140930160841.GB5098@wil.cx>
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On Tue, 30 Sep 2014 12:08:41 -0400, Matthew Wilcox said:
> 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.
I'm thinking of more than one place where that would be a feature, not a bug. :)
> What problem are you really trying to solve? Some big files hogging
> the page cache?
I'm officially a storage admin. I mostly support HPC and research. As
such, I'm always looking to add tools to my toolkit. :)
(And yes, I fully recognize that *in general*, this is a Bad Idea. However,
when you've got That One Problem Data File that *should* always be access
via O_DIRECT, and *usually* is accessed via O_DIRECT, and bad things happen
if something accesses it without it (for instance, when the file is 1.5X the
actual RAM), you start looking for fixes. If you've got another, more
sustainable way to say "do not let file /X/Y/Z hog the page cache" (and
no, LD_PRELOAD isn't sustainable the way chattr is, in my book), feel free to
recommend something. :)
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next prev parent reply other threads:[~2014-09-30 20:38 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-25 20:33 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
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 [this message]
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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