Messages in this thread | | | Date | Sun, 28 Jan 2007 10:01:32 -0800 | Subject | Re: lockmeter | From | Bill Huey (hui) <> |
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On Sun, Jan 28, 2007 at 09:38:16AM -0800, Martin J. Bligh wrote: > Christoph Hellwig wrote: > >On Sun, Jan 28, 2007 at 08:52:25AM -0800, Martin J. Bligh wrote: > >>Mmm. not wholly convinced that's true. Whilst i don't have lockmeter > >>stats to hand, the heavy time in __d_lookup seems to indicate we may > >>still have a problem to me. I guess we could move the spinlocks out > >>of line again to test this fairly easily (or get lockmeter upstream). > > > >We definitly should get lockmeter in. Does anyone volunteer for doing > >the cleanup and merged? > > On second thoughts .. I don't think it'd actually work for this since > the locks aren't global. Not that it shouldn't be done anyway, but ... > > ISTR we still thought dcache scalability was a significant problem last > time anyone looked at it seriously - just never got fixed. Dipankar?
My lock stat stuff shows dcache to a be a problem under -rt as well. It is keyed off the same mechanism as lockdep. It's pretty heavily hit under even normal loads relative to other kinds of lock overhead even for casual file operations on a 2x system. I can't imagine how lousy it's going to be under real load on a 8x or higher machine.
However, this pathc is -rt only and spinlock times are meaningless under it because of preemptiblity.
bill
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