Re: [PATCH 3/4] x86: save user rsp in pt_regs->sp on SYSCALL64 fastpath

From: Ingo Molnar
Date: Mon Mar 16 2015 - 05:44:42 EST



* Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx> wrote:

> > - but making it slower without really good reasons isn't good.
>
> The thinking here is that cleaning up entry.S is a good reason.
>
> We won't do anything which would slow it down by, say, 5%,
> but one cycle may be considered acceptable loss.

Ok, so I've applied this particular cleanup, in the hope that we can
recover those cycles on the now cleaner base.

If that doesn't work out then we can still re-introduce this
complication and see its maintainability in isolation, on a clean
base.

Thanks,

Ingo
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