linux-kernel - Re: [GIT PULL] execve updates for v6.8-rc1

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Date: Wed, 10 Jan 2024 11:24:24 -0800
From: Kees Cook <keescook@...omium.org>
To: Josh Triplett <josh@...htriplett.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Kees Cook <kees@...nel.org>, linux-kernel@...r.kernel.org,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [GIT PULL] execve updates for v6.8-rc1

On Tue, Jan 09, 2024 at 06:21:26PM -0800, Josh Triplett wrote:
> With Linus's fastpath patch ("no patch" with Linus's applied, and the
> followup -ENOMEM fix applied):
> 
> === With only PATH ===
> 0.28user 2.44system 0:02.80elapsed 97%CPU (0avgtext+0avgdata 1152maxresident)k
> 0inputs+0outputs (0major+694706minor)pagefaults 0swaps
> 
> === With 64 extra environment variables ===
> 0.29user 2.68system 0:03.06elapsed 97%CPU (0avgtext+0avgdata 1152maxresident)k
> 0inputs+0outputs (0major+712431minor)pagefaults 0swaps

Thanks for digging into this!

I've been trying to figure out how to measure only the execve portion of
a workload (with perf)[1] to get a more real-world measurement, but the
above does show improvements for the "open once early". I'll get the
behavior landed in -next after the merge window closes, and we can
continue examining if we can make do_filp_open() better...

-Kees

[1] https://lore.kernel.org/linux-perf-users/ZZ32p0LRSt5-vFPX@kernel.org/

-- 
Kees Cook