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Mateusz Guzik 14ef95be6f kernel/fork: group allocation/free of per-cpu counters for mm struct
A trivial execve scalability test which tries to be very friendly
(statically linked binaries, all separate) is predominantly bottlenecked
by back-to-back per-cpu counter allocations which serialize on global
locks.

Ease the pain by allocating and freeing them in one go.

Bench can be found here:
http://apollo.backplane.com/DFlyMisc/doexec.c

$ cc -static -O2 -o static-doexec doexec.c
$ ./static-doexec $(nproc)

Even at a very modest scale of 26 cores (ops/s):
before:	133543.63
after:	186061.81 (+39%)

While with the patch these allocations remain a significant problem,
the primary bottleneck shifts to page release handling.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20230823050609.2228718-3-mjguzik@gmail.com
[Dennis: reflowed 1 line]
Signed-off-by: Dennis Zhou <dennis@kernel.org>
2023-08-25 08:10:35 -07:00
arch x86: 2023-07-30 11:19:08 -07:00
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mm mm/percpu.c: print error message too if atomic alloc failed 2023-08-25 08:04:59 -07:00
net A patch to reduce the potential for erroneous RBD exclusive lock 2023-07-28 10:47:24 -07:00
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tools Probe fixes for 6.5-rc3: 2023-07-30 11:27:22 -07:00
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README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.