Messages in this thread | | | Date | Tue, 26 Jun 2012 20:45:42 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [RFC, PATCH] CLONE_NEWIPC and exit_group() |
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On Tue, Jun 26, 2012 at 05:04:57PM +0000, Serge E. Hallyn wrote: > Quoting Kirill A. Shutemov (kirill.shutemov@linux.intel.com): > > Hi, > > > > Patch to move kern_unmount() out of exit_group() code path is below. > > Dmitry, could you check if it's beneficial for your use-case? > > Hi, > > sorry, I don't seem to have the thread handy for contest. What is the > point of this? The work being moved was not being done under lock, > so what is this meant to gain?
It's basically addition to this patch (tested with the patch applied):
http://thread.gmane.org/gmane.linux.kernel.cifs/6347/focus=23929
Some context: Dmitry has workload which run a lot of short-living tasks in sandboxed environment. He noticed that exit_group() syscall of the last process in IPC namespace is a bottleneck.
The bottleneck was mainly due rcu_barrier() in kern_umount(). It's fixed by patch in the link (Andrew took it in -mm).
But probably having kern_umount() in exit_group() code path is not a good idea from scalability point of view?..
-- Kirill A. Shutemov [unhandled content-type:application/pgp-signature] | |