Re: BUG: Slowdown on 3000 socket-machines tracked down

[Andrew Morton]

Andi Kleen <ak@xxxxxx> wrote:
>
> In general to solve it one has to increase /proc/sys/vm/freepages
>  a lot.

/proc/sys/vm/min_free_kbytes

>  It would be nice though if the VM tuned itself dynamically to a lot
>  of GFP_ATOMIC requests. And maybe if GFP_ATOMIC was a bit more aggressive
>  and did some simple minded reclaiming that would be helpful too.
>  e.g. there could be a "easy to free" list in the VM for clean pages
>  where freeing is simple enough that it could be made interrupt safe.

I spose we could autotune the free memory thresholds somehow, if there is
good reason and a testcase.

Or we could run page reclaim from hard IRQ context - that could be a bit
expensive in terms of CPU consumption and latency though.

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