Messages in this thread | | | Date | Thu, 09 Jul 2009 04:54:10 +0000 (GMT) | From | NARAYANAN GOPALAKRISHNAN <> | Subject | Re: Re: Performance degradation seen after using one list for hot/cold pages. |
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> I'll add the rather important text: > > Fix a post-2.6.24 performance regression caused by > 3dfa5721f12c3d5a441448086bee156887daa961 ("page-allocator: preserve PFN > ordering when __GFP_COLD is set"). > > This was a pretty major screwup. > > This is why changing core MM is so worrisome - there's so much secret and > subtle history to it, and performance dependencies are unobvious and quite > indirect and the lag time to discover regressions is long. > > Narayanan, are you able to quantify the regression more clearly? All I > have is "2 MBps lower" which isn't very useful. What is this as a > percentage, and with what sort of disk controller? Thanks.
It is around 15%. There is no disk controller as our setup is based on Samsung OneNAND used as a memory mapped device on a OMAP2430 based board.
Narayanan
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