Re: [PATCH 2/2] futex: lockless wakeups

From: Davidlohr Bueso
Date: Mon Apr 20 2015 - 13:31:27 EST


On Mon, 2015-04-20 at 16:57 +0200, Peter Zijlstra wrote:
> Haha, you dug that out did you ;-)
>
> Does this patch on its own actually help anything? Back when I wrote
> that there was the vague hope it would actually help some of the
> client-server ping-pong workloads, where the client does sync requests
> to the server.
>
> In that case, if the server can handle the req. while the client yields
> we've saved on an expensive wakeup.
>
> Reality never really worked out for that -- even after we fixed a few
> boot and runtime issues with it.

I had boot problems about 2 years ago (even with qemu) with it.
Nowadays, I cannot trigger any issues with it. And on a large machine
I've been using it just fine, throwing a lot of workloads at it. All in
all my schedule auditing has only been by searching the code, not from
this patch.

Thanks,
Davidlohr

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