Messages in this thread | | | From | "Hua Zhong" <> | Subject | RE: [PATCH] likely cleanup: revert unlikely in ll_back_merge_fn | Date | Tue, 25 Apr 2006 14:38:58 -0700 |
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It seems that new BIOs do not have BIO_SEG_VALID set. So when you do sequential IO, the IO being back-merged should always have not had valid segments.
I ran bonnie++ and it shows the same thing.
> Well you'd want to optimize for the busy case, right, no > point in optimizing for a more idle system. > > I'm not at all uninterested in this, I'd just like to see a > more intelligent/controlled work load that actually stresses > the io subsystem being profiled. If you have a not-so-busy > system, you like don't do enough IO to trigger a lot of > merges. Or maybe you do, and we just have a bug somewhere so > that we unfortunately repeatedly recount segments. > > Care to run a simple io benchmark and profile that? > > -- > Jens Axboe >
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