From: Andy Lutomirski <luto@amacapital.net>
To: Andrew Morton <akpm@linux-foundation.org>,
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 v10 00/21] Support ext4 on NV-DIMMs
Date: Wed, 27 Aug 2014 18:30:27 -0700 [thread overview]
Message-ID: <53FE8633.10305@amacapital.net> (raw)
In-Reply-To: <20140827144622.ed81195a1d94799bb57a3207@linux-foundation.org>
On 08/27/2014 02:46 PM, Andrew Morton wrote:
> I assume (because I wasn't told!) that there are two objectives here:
>
> 1) reduce memory consumption by not maintaining pagecache and
> 2) reduce CPU cost by avoiding the double-copies.
>
> These things are pretty easily quantified. And really they must be
> quantified as part of the developer testing, because if you find
> they've worsened then holy cow, what went wrong.
>
There are two more huge ones:
3) Writes via mmap are immediately durable (or at least they're durable
after a *very* lightweight flush).
4) No page faults ever once a page is writable (I hope -- I'm not sure
whether this series actually achieves that goal).
A note on #3: there is ongoing work to enable write-through memory for
things like this. Once that's done, then writes via mmap might actually
be synchronously durable, depending on chipset details.
--Andy
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next prev parent reply other threads:[~2014-08-28 1:30 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-27 3:45 Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 01/21] axonram: Fix bug in direct_access Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 02/21] Change direct_access calling convention Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 03/21] Fix XIP fault vs truncate race Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 04/21] Allow page fault handlers to perform the COW Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 05/21] Introduce IS_DAX(inode) Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 06/21] Add copy_to_iter(), copy_from_iter() and iov_iter_zero() Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 07/21] Replace XIP read and write with DAX I/O Matthew Wilcox
2014-09-14 14:11 ` Boaz Harrosh
2014-08-27 3:45 ` [PATCH v10 08/21] Replace ext2_clear_xip_target with dax_clear_blocks Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 09/21] Replace the XIP page fault handler with the DAX page fault handler Matthew Wilcox
2014-09-03 7:47 ` Dave Chinner
2014-09-10 15:23 ` Matthew Wilcox
2014-09-11 3:09 ` Dave Chinner
2014-09-24 15:43 ` Matthew Wilcox
2014-09-25 1:01 ` Dave Chinner
2014-08-27 3:45 ` [PATCH v10 10/21] Replace xip_truncate_page with dax_truncate_page Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 11/21] Replace XIP documentation with DAX documentation Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 12/21] Remove get_xip_mem Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 13/21] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 14/21] ext2: Remove ext2_use_xip Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 15/21] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 16/21] Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 17/21] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 18/21] Get rid of most mentions of XIP in ext2 Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 19/21] xip: Add xip_zero_page_range Matthew Wilcox
2014-09-03 9:21 ` Dave Chinner
2014-09-04 21:08 ` Matthew Wilcox
2014-09-04 21:36 ` Theodore Ts'o
2014-09-08 18:59 ` Matthew Wilcox
2014-08-27 3:45 ` [PATCH v10 20/21] ext4: Add DAX functionality Matthew Wilcox
2014-09-03 11:13 ` Dave Chinner
2014-09-10 16:49 ` Boaz Harrosh
2014-09-11 4:38 ` Dave Chinner
2014-09-14 12:25 ` Boaz Harrosh
2014-09-15 6:15 ` Dave Chinner
2014-09-15 9:41 ` Boaz Harrosh
2014-08-27 3:45 ` [PATCH v10 21/21] brd: Rename XIP to DAX Matthew Wilcox
2014-08-27 20:06 ` [PATCH v10 00/21] Support ext4 on NV-DIMMs Andrew Morton
2014-08-27 21:12 ` Matthew Wilcox
2014-08-27 21:46 ` Andrew Morton
2014-08-28 1:30 ` Andy Lutomirski [this message]
2014-08-28 16:50 ` Matthew Wilcox
2014-08-28 15:45 ` Matthew Wilcox
2014-08-27 21:22 ` Christoph Lameter
2014-08-27 21:30 ` Andrew Morton
2014-08-27 23:04 ` One Thousand Gnomes
2014-08-28 7:17 ` Dave Chinner
2014-08-30 23:11 ` Christian Stroetmann
2014-08-28 8:08 ` Boaz Harrosh
2014-08-28 22:09 ` Zwisler, Ross
2014-09-03 12:05 ` [PATCH 1/1] xfs: add DAX support Dave Chinner
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