From: Dave Chinner <david@fromorbit.com>
To: "Al Lau (alau2)" <alau2@cisco.com>
Cc: "xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: mkfs.xfs -n size=65536
Date: Tue, 13 Oct 2015 11:23:08 +1100 [thread overview]
Message-ID: <20151013002308.GI27164@dastard> (raw)
In-Reply-To: <0F279340237AA148AD7E3C6A70561A5E01266BE7@xmb-rcd-x14.cisco.com>
On Fri, Oct 09, 2015 at 10:40:00PM +0000, Al Lau (alau2) wrote:
> I am looking for more details on the "-n size=65536" option in
> mkfs.xfs. The question is the memory allocation this option
> generates. The system is Redhat EL 7.0
> (3.10.0-229.1.2.el7.x86_64).
>
> We have been getting this memory allocation deadlock message in
> the /var/log/messages file. The file system is used for ceph OSD
> and it has about 531894 files.
So, if you only have half a million files being stored, why would you
optimised the directory structure for tens of millions of files in a
single directory?
> Oct 6 07:11:09 abc-ceph1-xyz kernel: XFS: possible memory allocation deadlock in kmem_alloc (mode:0x8250)
mode = ___GFP_WAIT | ___GFP_IO | ___GFP_NOWARN | ___GFP_ZERO
= GFP_NOFS | GFP_ZERO | GFP_NOWARN
which means it's come through kmem_zalloc() and so is a heap
allocation and hence probably quite small.
Hence I doubt that has anything to do with the directory
block size, as the directory blocks are allocated as single pages
through a completely allocation different path and them virtually
mapped...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2015-10-13 0:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-09 22:40 mkfs.xfs -n size=65536 Al Lau (alau2)
2015-10-13 0:23 ` Dave Chinner [this message]
2015-10-13 1:39 ` Al Lau (alau2)
2015-10-13 3:33 ` Dave Chinner
2015-10-13 3:42 ` Al Lau (alau2)
2015-10-13 3:55 ` Al Lau (alau2)
2015-10-13 4:30 ` Dave Chinner
2015-10-13 7:28 ` Al Lau (alau2)
2015-10-13 8:25 ` Dave Chinner
2015-11-06 2:06 ` Al Lau (alau2)
2015-10-13 4:04 ` Al Lau (alau2)
2015-10-13 22:05 ` Al Lau (alau2)
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