Re: [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory

[Andi Kleen]

Mel Gorman <mel@xxxxxxxxx> writes:
>
> If vm_enough_memory is being heavily hit as well, it implies that this
> workload is mmap-intensive which is pretty inefficient in itself. I

Saw it with tmpfs originally. No need to be mmap intensive. Just
do lots of IOs on tmpfs.

> guess it would also apply to workloads that are malloc-intensive for
> large buffers but I'd expect the cache line bounces to only dominate if
> there was little or no computation on the resulting buffers.

I think you severly underestimate the costs of bouncing cache lines
on >2S.

> As a result, I wonder how realistic is this test workload and who useful
> fixing this problem is in general?

It's kind of bad if tmpfs doesn't scale.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/