From: Boaz Harrosh <boaz@plexistor.com>
To: Dave Hansen <dave.hansen@linux.intel.com>,
Boaz Harrosh <boaz@plexistor.com>,
Dave Chinner <david@fromorbit.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@osdl.org>, "H. Peter Anvin" <hpa@zytor.com>,
Hugh Dickins <hughd@google.com>, Ingo Molnar <mingo@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, Matthew Wilcox <willy@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org
Subject: Re: [PATCH] dax, pmem: add support for msync
Date: Wed, 02 Sep 2015 18:18:06 +0300 [thread overview]
Message-ID: <55E7132E.104@plexistor.com> (raw)
In-Reply-To: <55E70653.4090302@linux.intel.com>
On 09/02/2015 05:23 PM, Dave Hansen wrote:
<>
> I'd be curious what the cost is in practice. Do you have any actual
> numbers of the cost of doing it this way?
>
> Even if the instruction is a "noop", I'd really expect the overhead to
> really add up for a tens-of-gigabytes mapping, no matter how much the
> CPU optimizes it.
What tens-of-gigabytes mapping? I have yet to encounter an application
that does that. Our tests show that usually the mmaps are small.
I can send you a micro benchmark results of an mmap vs direct-io random
write. Our code will jump over holes in the file BTW, but I'll ask to also
run it with falloc that will make all blocks allocated.
Give me a few days to collect this.
I guess one optimization we should do is jump over holes and zero-extents.
This will save the case of a mostly sparse very big file.
Thanks
Boaz
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next prev parent reply other threads:[~2015-09-02 15:18 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-31 18:59 [PATCH] dax, pmem: add support for msync Ross Zwisler
2015-08-31 19:06 ` Christoph Hellwig
2015-08-31 19:26 ` Ross Zwisler
2015-08-31 19:34 ` Christoph Hellwig
2015-08-31 23:38 ` Dave Chinner
2015-09-01 7:06 ` Christoph Hellwig
2015-09-01 12:18 ` Boaz Harrosh
2015-09-02 19:04 ` Ross Zwisler
2015-09-02 20:17 ` Kirill A. Shutemov
2015-09-03 6:32 ` Boaz Harrosh
2015-09-03 16:44 ` Ross Zwisler
2015-09-01 22:21 ` Dave Chinner
2015-09-02 3:19 ` Ross Zwisler
2015-09-02 5:17 ` Dave Chinner
2015-09-02 10:27 ` Boaz Harrosh
2015-09-02 14:23 ` Dave Hansen
2015-09-02 15:18 ` Boaz Harrosh [this message]
2015-09-02 15:39 ` Dave Hansen
2015-09-02 16:00 ` Boaz Harrosh
2015-09-02 16:19 ` Dave Hansen
2015-09-03 6:41 ` Boaz Harrosh
2015-09-02 10:04 ` Boaz Harrosh
2015-09-01 10:08 ` Kirill A. Shutemov
2015-09-01 11:27 ` Boaz Harrosh
2015-09-01 22:49 ` Dave Chinner
2015-09-02 9:13 ` Kirill A. Shutemov
2015-09-02 9:37 ` Boaz Harrosh
2015-09-02 9:41 ` Boaz Harrosh
2015-09-02 9:47 ` Kirill A. Shutemov
2015-09-02 10:28 ` Boaz Harrosh
2015-09-03 0:57 ` Dave Chinner
2015-09-01 13:12 ` Boaz Harrosh
2015-09-02 17:47 ` Ross Zwisler
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