Messages in this thread |  | | | Date | Fri, 16 Sep 2005 13:12:16 +1000 | | From | Nick Piggin <> | | Subject | Re: New lockless pagecache |
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Alok kataria wrote: > Hi Nick, > > I have collected performance numbers for the lock less page cache > patch on the AIM - IO test. > The performance numbers are collected for 1-100 tasks 1-50 tasks and > 90-100 tasks both for with and without your patch. This was done on > 2.6.13 kernel. > There's definite improvement when the tasks are small i.e ~50-70. But > when the tasks go beyond 80, we see a large performance dip. > I again profiled the 90-100 runs with spinlock's inlined, but couldn't > understand the reason behind the performance difference. > > Please find attached the performance numbers as well as the oprofile logs. >
Hi Alok,
Thanks very much for doing these numbers. Performance is improved significantly at smaller numbers of tasks, as you say.
Unfortunately I can't pinpoint the reason why performance drops at larger numbers. I could assume that the last remaining place that used read_lock_irq for the tree_lock (wait_on_page_writeback_range) got hurt when switching to spinlocks, but that would seem vary unlikely.
I'll have to look into it further.
Thanks, Nick
-- SUSE Labs, Novell Inc.
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