Messages in this thread | | | From | Ben Hutchings <> | Date | Sat, 20 Nov 2010 02:16:12 +0000 | Subject | Re: [Stable-review] [08/45] mm, x86: Saving vmcore with non-lazy freeing of vmas |
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On Fri, 2010-11-19 at 13:42 -0800, Greg KH wrote: > 2.6.32-stable review patch. If anyone has any objections, please let us know. > > ------------------ > > From: Cliff Wickman <cpw@sgi.com> > > commit 3ee48b6af49cf534ca2f481ecc484b156a41451d upstream. > > During the reading of /proc/vmcore the kernel is doing > ioremap()/iounmap() repeatedly. And the buildup of un-flushed > vm_area_struct's is causing a great deal of overhead. (rb_next() > is chewing up most of that time). > > This solution is to provide function set_iounmap_nonlazy(). It > causes a subsequent call to iounmap() to immediately purge the > vma area (with try_purge_vmap_area_lazy()). > > With this patch we have seen the time for writing a 250MB > compressed dump drop from 71 seconds to 44 seconds. [...]
Useful, but it doesn't seem to meet the criteria for stable updates.
Ben.
-- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse. [unhandled content-type:application/pgp-signature] | |