Messages in this thread |  | | Date | Thu, 12 Jul 2001 11:26:13 +0200 | From | Andi Kleen <> | Subject | Re: [lvm-devel] Re: 2x Oracle slowdown from 2.2.16 to 2.4.4 |
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On Thu, Jul 12, 2001 at 04:30:46AM +0200, Andrea Arcangeli wrote: > I will soon somehow make those changes in the lvm (based on beta7) in my > tree and it will be interesting to see if this will make a difference. I > will also have a look to see if I can improve a little more the lvm_map > but other than those non rw semaphores there should be not a significant > overhead to remove in the lvm fast path.
Even if you fix the snapshot_sem you still have the down on the _pe_lock in lvm_map. The part covered by the PE lock is only a few tenths of cycles shorter than the part covered by the snapshot semaphore; so it is unlikely that you see much difference unless you change both to rwsems.
Wouldn't a single semaphore be enough BTW to cover both?
-Andi
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