Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()

From: Linus Torvalds
Date: Fri Jan 08 2010 - 12:53:40 EST




On Fri, 8 Jan 2010, Christoph Lameter wrote:
>
> Can we at least consider a typical standard business server, dual quad
> core hyperthreaded with 16 "cpus"? Cacheline contention will increase
> significantly there.

I bet it won't be a problem. It's when things go cross-socket that they
suck. So 16 cpu's across two sockets I wouldn't worry about.

> > Because let's face it - if your workload does several million page faults
> > per second, you're just doing something fundamentally _wrong_.
>
> You may just want to get your app running and its trying to initialize
> its memory in parallel on all threads. Nothing wrong with that.

Umm. That's going to be limited by the memset/memcpy, not the rwlock, I
bet.

The benchmark in question literally did a single byte write to each page
in order to show just the kernel component. That really isn't realistic
for any real load.

Linus
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