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From: Brandon Casey <casey@nrlssc.navy.mil>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alex Riesen <raa.lkml@gmail.com>,
	Bevan Watkiss <bevan.watkiss@cloakware.com>,
	Git Mailing List <git@vger.kernel.org>
Subject: Re:
Date: Fri, 08 May 2009 12:43:52 -0500	[thread overview]
Message-ID: <OWEdfN5mNBoNl1TcdOvhhNfi_nLsao-aFrHkz_rNtuX_4lqXHisfcQ@cipher.nrlssc.navy.mil> (raw)
In-Reply-To: <Ah7lj3UWxgwxNiQs6kqiiVurulv4F00ssWrb3OzfTrXYlK8ZBCSBOQ@cipher.nrlssc.navy.mil>

Brandon Casey wrote:
> Linus Torvalds wrote:
>> And 
>> the preloading sounds like it hits serialization overhead in the kernel, 
>> which I'm not at all surprised at, but not being surprised doesn't mean 
>> that I'm not interested to hear where it is.
>>
>> The Linux VFS dcache itself should scale better than that (but who knows - 
>> cacheline ping-pong due to lock contention can easily cause a 10x slowdown 
>> even without being _totally_ contended all the time). So I would _suspect_ 
>> that it's some NFS lock that you're seeing, but I'd love to know more.
>>
>> Btw, those system times are pretty high to begin with, so I'd love to know 
>> kernel version and see a profile even without the parallel case and 
>> presumably lock contention.

Here's an strace of 'git checkout':

Before (cold cache):
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 98.60    6.365501         111     57432           lstat64
  0.50    0.031984         359        89         2 close
  0.25    0.015818         115       137        77 open
  0.12    0.007670          23       339           write
  0.09    0.005631         110        51           munmap
  0.08    0.004873          49        99        69 stat64
  0.07    0.004771         140        34        15 access
  0.05    0.003083         280        11         5 waitpid
  0.05    0.002973          10       284           brk
  0.04    0.002816         469         6           execve
<snip>

After (cold cache, no lstat fix, just cache_preload):
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 90.90   23.717981         413     57432           lstat64
  8.72    2.273917      162423        14         2 futex
  0.12    0.032241         948        34           close
  0.04    0.011507         202        57           munmap
  0.04    0.009648         132        73           mmap2
  0.03    0.008508         149        57        20 open
  0.03    0.007771         311        25           mprotect
  0.03    0.007758         388        20           clone
  0.03    0.007548          23       334           write
  0.02    0.005247         262        20        10 access

-brandon

  reply	other threads:[~2009-05-08 17:44 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-07 17:01 (unknown), Bevan Watkiss
2009-05-07 17:13 ` Alex Riesen
2009-05-07 17:26   ` Bevan Watkiss
2009-05-07 18:18     ` Alex Riesen
2009-05-07 18:48       ` Bevan Watkiss
2009-05-07 19:56         ` Björn Steinbrink
2009-05-07 18:56     ` Linus Torvalds
2009-05-07 19:37       ` RE: Bevan Watkiss
2009-05-07 20:07         ` RE: Linus Torvalds
2009-05-07 20:20           ` RE: Linus Torvalds
2009-05-07 20:43             ` Junio C Hamano
2009-05-07 21:33               ` Re: Linus Torvalds
2009-05-07 21:55             ` Linus Torvalds
2009-05-07 22:27               ` RE: david
2009-05-07 22:36                 ` RE: Linus Torvalds
2009-05-07 22:43                   ` RE: david
2009-05-07 23:00                     ` RE: Linus Torvalds
2009-05-07 23:07                       ` RE: david
2009-05-07 23:18                         ` RE: Linus Torvalds
2009-05-07 23:31                           ` RE: david
2009-05-07 23:57                             ` Johan Herland
2009-05-08 16:14                             ` Bevan Watkiss
2009-05-08  8:17               ` Alex Riesen
2009-05-08 14:39                 ` Re: Linus Torvalds
2009-05-08 15:51                   ` Re: Brandon Casey
2009-05-08 16:15                     ` Re: Linus Torvalds
2009-05-08 17:27                       ` Re: Brandon Casey
2009-05-08 17:43                         ` Brandon Casey [this message]
2009-05-08 21:49                           ` Re: Linus Torvalds
2009-05-08 23:04                             ` Re: Brandon Casey
2009-05-09 16:44                               ` Re: Linus Torvalds
2009-05-08 17:44                         ` Re: Linus Torvalds
2009-05-08 16:47               ` 'git checkout' and unlink() calls (was: Re: ) Kjetil Barvik
2009-05-08 17:57                 ` Linus Torvalds
     [not found] <20220301070226.2477769-1-jaydeepjd.8914>
2022-03-06 11:10 ` Jaydeep P Das
2022-03-06 11:22   ` Jaydeep Das
  -- strict thread matches above, loose matches on Subject: below --
2021-08-21 14:40 TECOB270_Ganesh Pawar
2021-08-21 23:52 ` Jeff King
2019-11-15 16:03 Martin Nicolay
2019-11-15 16:29 ` Martin Ågren
2019-11-15 16:37   ` Re: Martin Ågren
2019-08-20 17:23 William Baker
2019-08-20 17:27 ` Yagnatinsky, Mark
2019-03-05 14:57 [GSoC][PATCH v2 3/3] t3600: use helpers to replace test -d/f/e/s <path> Eric Sunshine
2019-03-05 23:38 ` Rohit Ashiwal
2019-01-23 10:50 Christopher Hagler
2019-01-23 14:16 ` Cody Kratzer
2019-01-23 14:25   ` Re: Thomas Braun
2019-01-23 16:00   ` Re: Christopher Hagler
2019-01-23 16:35     ` Randall S. Becker
2019-01-24 17:11   ` Johannes Schindelin
2018-10-08 13:33 Netravnen
2018-10-08 13:34 ` Inderpreet Saini
2018-04-27  0:54 [PATCH v3 2/3] merge: Add merge.renames config setting Ben Peart
2018-04-27 18:19 ` Elijah Newren
2018-04-30 13:11   ` Ben Peart
2018-04-30 16:12     ` Re: Elijah Newren
2018-05-02 14:33       ` Re: Ben Peart
2018-02-27  1:18 Alan Gage
2018-02-27 10:26 ` René Scharfe
2017-11-20 15:10 Viet Nguyen
2017-11-20 20:07 ` Stefan Beller
2017-11-12  2:21 hsed
2017-11-13 18:56 ` Stefan Beller
2017-01-25  0:11 [PATCH 7/7] completion: recognize more long-options Cornelius Weig
2017-01-25  0:21 ` Stefan Beller
2017-01-25  0:43   ` Cornelius Weig
2017-01-25  0:52     ` Re: Stefan Beller
2017-01-25  0:54   ` Re: Linus Torvalds
2017-01-25  1:32     ` Re: Eric Wong
2016-04-11 19:04 (unknown), miwilliams
2016-04-12  4:33 ` Stefan Beller
2015-08-19 19:41 Re: christain147
2015-08-19 11:09 Re: christain147
2015-08-05 12:47 (unknown) Ivan Chernyavsky
2015-08-15  9:19 ` Duy Nguyen
2015-08-17 17:49   ` Re: Junio C Hamano
2015-04-08 20:44 (unknown), Mamta Upadhyay
2015-04-08 21:58 ` Thomas Braun
2015-04-09 11:27   ` Re: Konstantin Khomoutov
     [not found] <CANSxx61FaNp5SBXJ8Y+pWn0eDcunmibKR5g8rttnWGdGwEMHCA@mail.gmail.com>
2015-03-18 20:45 ` Re: Junio C Hamano
2015-03-18 21:06   ` Re: Stefan Beller
2015-03-18 21:17     ` Re: Jeff King
2015-03-18 21:28       ` Re: Jeff King
2015-03-18 21:33         ` Re: Junio C Hamano
2015-03-18 21:45           ` Re: Stefan Beller
2015-03-13  1:34 (unknown) cody.taylor
2015-03-13  2:00 ` Duy Nguyen
2014-09-08 11:36 (unknown), R. Klomp
     [not found] ` <CAOqJoqGSRUw_UT4LhqpYX-WX6AEd2ReAWjgNS76Cra-SMKw3NQ@mail.gmail.com>
2014-09-08 14:36   ` R. Klomp
2014-09-10  0:00     ` Re: David Aguilar
2014-09-15 15:10       ` Re: R. Klomp
2014-02-06 11:54 "Sparse checkout leaves no entry on working directory" all the time on Windows 7 on Git 1.8.5.2.msysgit.0 konstunn
2014-02-06 13:20 ` Johannes Sixt
2014-02-06 19:56   ` Constantine Gorbunov
2012-06-12 21:12 (unknown), rohit sood
2012-06-12 23:51 ` Erik Faye-Lund
2009-11-18  5:03 Re: Anna
2009-05-11 18:57 (unknown) Don Slutz
2009-05-11 20:48 ` Johannes Schindelin
2009-05-12 12:45   ` Re: Don Slutz
2009-03-30  5:03 (unknown), David Aguilar
2009-03-30  7:02 ` Markus Heidelberg
2009-03-30  8:46   ` Re: Junio C Hamano
2007-11-01 20:44 (unknown), Francesco Pretto
2007-11-01 20:48 ` Francesco Pretto
2006-02-02  0:39 [RFC & PATCH] Solaris 8: ENOSYS when mkdir applied to automount., Jason Riedy
2006-02-02  4:18 ` H. Peter Anvin
2005-04-22 22:19 (unknown), atani
2005-04-22 23:16 ` Martin Schlemmer

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