Re: [PATCH v3 0/1] pipe: only enable the extra wake_up(rd_wait) for edge-triggered consumers

Linus Torvalds <[email protected]> Thu, 30 Jul 2026 09:36:35 -0700
Newsgroups org.kernel.vger.io-uring,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel
Message-ID <CAHk-=wi7EccGaeo2Q5mdcvcQJ8VX7tcJWW2fHkg6vfmHGGX8AA@mail.gmail.com>
On Thu, 30 Jul 2026 at 07:12, Oleg Nesterov <[email protected]> wrote:
>
> Let me repeat, I do not think this patch can improve performance. In fact
> I only hope that none of (micro)benchmarks will suffer, they are often
> very sensitive to any changes in pipe.c

I like this patch mostly for the renaming, not because I think it
matters. I think "poll usage" was a mistake in naming and doesn't
explain the issue. That said, I'd go even further, and make it clear
that it's not about "poll" itself - which is fine, it's about "epoll",
which has that broken crazy bug where it calls something "edge
triggered" but then actually wants effectively level-triggered
behavior - wakeups when nothing actually changed, which is the
*opposite* of an edge.

Pure garbage.

So the real name should be something like "epoll_pseudo_edgetrigger".
Because "et" isn't really helpful either.

             Linus