1. 07 May, 2013 2 commits
  2. 19 Feb, 2013 1 commit
    • Yuanhan Liu's avatar
      rwsem-spinlock: Implement writer lock-stealing for better scalability · 41ef8f82
      Yuanhan Liu authored
      We (Linux Kernel Performance project) found a regression
      introduced by commit:
      
        5a505085 mm/rmap: Convert the struct anon_vma::mutex to an rwsem
      
      which converted all anon_vma::mutex locks rwsem write locks.
      
      The semantics are the same, but the behavioral difference is
      quite huge in some cases. After investigating it we found the
      root cause: mutexes support lock stealing while rwsems don't.
      
      Here is the link for the detailed regression report:
      
        https://lkml.org/lkml/2013/1/29/84
      
      Ingo suggested adding write lock stealing to rwsems:
      
          "I think we should allow lock-steal between rwsem writers - that
           will not hurt fairness as most rwsem fairness concerns relate to
           reader vs. writer fairness"
      
      And here is the rwsem-spinlock version.
      
      With this patch, we got a double performance increase in one
      test box with following aim7 workfile:
      
          FILESIZE: 1M
          POOLSIZE: 10M
          10 fork_test
      
       /usr/bin/time output w/o patch                       /usr/bin/time_output with patch
       -- Percent of CPU this job got: 369%                 Percent of CPU this job got: 537%
       Voluntary context switches: 640595016                Voluntary context switches: 157915561
      
      We got a 45% increase in CPU usage and saved about 3/4 voluntary context switches.
      Reported-by: 's avatarLKP project <lkp@linux.intel.com>
      Suggested-by: 's avatarIngo Molnar <mingo@kernel.org>
      Signed-off-by: 's avatarYuanhan Liu <yuanhan.liu@linux.intel.com>
      Cc: Alex Shi <alex.shi@intel.com>
      Cc: David Howells <dhowells@redhat.com>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Anton Blanchard <anton@samba.org>
      Cc: Arjan van de Ven <arjan@linux.intel.com>
      Cc: paul.gortmaker@windriver.com
      Link: http://lkml.kernel.org/r/1359716356-23865-1-git-send-email-yuanhan.liu@linux.intel.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>
      41ef8f82
  3. 07 Mar, 2012 1 commit
  4. 13 Sep, 2011 1 commit
  5. 07 Apr, 2010 1 commit
  6. 15 Dec, 2009 2 commits
  7. 08 Feb, 2008 1 commit
  8. 11 Oct, 2006 1 commit
  9. 03 Jul, 2006 2 commits
  10. 01 May, 2005 1 commit
  11. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4