RE: Linux and huge pages
Date: Thu, 24 Jan 2013 10:06:43 -0600
Message-ID: <F05D8DF1FB25F44085DB74CB916678E8856C2C93FA_at_NADCWPMSGCMS10.hca.corpad.net>
Oh I just realized in Yong's example, it actually lists the page size :)
I'm not on 2.6.29 tho so that entry is not in my smaps. So perhaps my deduction would work on previous kernel versions - not sure.
Chris
-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Yong Huang
Sent: Thursday, January 24, 2013 9:43 AM
To: Mark.Bobak_at_proquest.com
Cc: oracle-l_at_freelists.org
Subject: RE: Linux and huge pages
> Unfortunately, if you're looking to directly confirm whether a
> particular memory segment was allocated with hugepages, I know of no
> way to do that.
There's no v$ or x$ table for this info, but /proc/<pid>/smaps has KernelPageSize and MMUPageSize if your kernel is new enough, probably 2.6.29 or newer. For example, the following shows a shared memory segment of about 37GB using 2MB page size of HugePages.
70000000-960000000 rwxs 00000000 00:0c 1179654 /SYSV00000000 (deleted) Size: 37486592 kB Rss: 0 kB Pss: 0 kB Shared_Clean: 0 kB Shared_Dirty: 0 kB Private_Clean: 0 kB Private_Dirty: 0 kB Referenced: 0 kB Anonymous: 0 kB AnonHugePages: 0 kB Swap: 0 kB KernelPageSize: 2048 kB MMUPageSize: 2048 kB
Regarding the kernel version, my note says "[when] this patch is in your kernel: http://lkml.org/lkml/2008/10/3/250. That patch may be in kernel 2.6.29 (http://www.kernel.org/pub/linux/kernel/v2.6/)".
Yong Huang
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