From: Liang Zhen <liang@whamcloud.com>
Date: Tue, 1 Jan 2013 08:23:09 +0000 (+0800)
Subject: LU-2432 ptlrpc: alloc_rqbd spin on vmap_area_lock
X-Git-Tag: 2.3.59~67
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=be025f5580a0cc4958267d2e4317aac4e2ebc0c3;hp=be025f5580a0cc4958267d2e4317aac4e2ebc0c3

LU-2432 ptlrpc: alloc_rqbd spin on vmap_area_lock

vmalloc based allocations can potentially take a very long time to
complete due to a regression in the kernel. As a result, MDS service
threads might lock up for certain periods of time while all of the
cores spin on the vmap_area_lock down in ptlrpc_alloc_rqbd.

Tihs patch only allow one thread of each CPT to enter rqbd
alloation path.

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I4ba442801859ae58cf8e8dd8ae18af1062379639
Reviewed-on: http://review.whamcloud.com/4939
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Prakash Surya <surya1@llnl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
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