From: Oleg Nesterov <oleg@redhat.com>
To: Mateusz Guzik <mjguzik@gmail.com>
Cc: kernel test robot <oliver.sang@intel.com>,
oe-lkp@lists.linux.dev, lkp@intel.com,
Christian Brauner <brauner@kernel.org>,
WangYuli <wangyuli@uniontech.com>,
linux-fsdevel@vger.kernel.org
Subject: Re: [linux-next:master] [pipe_read] aaec5a95d5: stress-ng.poll.ops_per_sec 11.1% regression
Date: Mon, 20 Jan 2025 13:22:56 +0100 [thread overview]
Message-ID: <20250120121928.GA7432@redhat.com> (raw)
In-Reply-To: <leot53sdd6es2xsnljub4rr4n3xgusft6huntr437wmaoo5rob@hhbtzrwgxel2>
On 01/20, Mateusz Guzik wrote:
>
> Whatever the long term fate of the patch I think it would be prudent to
> skip it in this merge window.
Perhaps... I'll try to take another look tomorrow.
Just one note right now.
> First two notes:
> 1. the change only considers performing a wake up if the current
> source buf got depleted -- if there is a blocked writer and there is at
> least one byte in the current buf nothing happens, which is where the
> difference in results is coming from
Sorry I don't understand. Unless this patch is buggy, pipe_read() must
always wakeup a blocked writer if the writer can write at least one byte.
The writer can't write to "current" buf = pipe->bufs[tail & mask] if
pipe_full() is still true.
Oleg.
next prev parent reply other threads:[~2025-01-20 12:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-20 6:57 [linux-next:master] [pipe_read] aaec5a95d5: stress-ng.poll.ops_per_sec 11.1% regression kernel test robot
2025-01-20 11:27 ` Mateusz Guzik
2025-01-20 12:22 ` Oleg Nesterov [this message]
2025-01-20 12:42 ` Oleg Nesterov
2025-01-20 14:43 ` Oleg Nesterov
2025-01-20 16:56 ` Mateusz Guzik
2025-01-20 20:31 ` Oleg Nesterov
2025-01-20 21:15 ` Mateusz Guzik
2025-01-23 12:56 ` Oleg Nesterov
2025-01-20 15:50 ` Oleg Nesterov
2025-01-22 8:43 ` Oliver Sang
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