Messages in this thread | | | Date | Sun, 14 Mar 2004 15:22:53 -0800 | From | Andrew Morton <> | Subject | Re: [2.4] heavy-load under swap space shortage |
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Andrea Arcangeli <andrea@suse.de> wrote: > > > > > Having a magic knob is a weak solution: the majority of people who are > > affected by this problem won't know to turn it on. > > that's why I turned it _on_ by default in my tree ;)
So maybe Marcelo should apply this patch, and also turn it on by default.
> There are workloads where adding anonymous pages to the lru is > suboptimal for both the vm (cache shrinking) and the fast path too > (lru_cache_add), not sure how 2.6 optimizes those bits, since with 2.6 > you're forced to add those pages to the lru somehow and that implies > some form of locking.
Basically a bunch of tweeaks:
- Per-zone lru locks (which implicitly made them per-node)
- Adding/removing sixteen pages for one taking of the lock.
- Making the lock irq-safe (it had to be done for other reasons, but reduced contention by 30% on 4-way due to not having a CPU wander off to service an interrupt while holding a critical lock).
- In page reclaim, snip 32 pages off the lru completely and drop the lock while we go off and process them.
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