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Chengming Zhou bb29fd7760 mm/zswap: make sure each swapfile always have zswap rb-tree 
Patch series "mm/zswap: optimize the scalability of zswap rb-tree", v2.

When testing the zswap performance by using kernel build -j32 in a tmpfs
directory, I found the scalability of zswap rb-tree is not good, which is
protected by the only spinlock.  That would cause heavy lock contention if
multiple tasks zswap_store/load concurrently.

So a simple solution is to split the only one zswap rb-tree into multiple
rb-trees, each corresponds to SWAP_ADDRESS_SPACE_PAGES (64M).  This idea
is from the commit 4b3ef9daa4 ("mm/swap: split swap cache into 64MB
trunks").

Although this method can't solve the spinlock contention completely, it
can mitigate much of that contention.  Below is the results of kernel
build in tmpfs with zswap shrinker enabled:

     linux-next  zswap-lock-optimize
real 1m9.181s    1m3.820s
user 17m44.036s  17m40.100s
sys  7m37.297s   4m54.622s

So there are clearly improvements.  And it's complementary with the
ongoing zswap xarray conversion by Chris.  Anyway, I think we can also
merge this first, it's complementary IMHO.  So I just refresh and resend
this for further discussion.


This patch (of 2):

Not all zswap interfaces can handle the absence of the zswap rb-tree,
actually only zswap_store() has handled it for now.

To make things simple, we make sure each swapfile always have the zswap
rb-tree prepared before being enabled and used.  The preparation is
unlikely to fail in practice, this patch just make it explicit.

Link: https://lkml.kernel.org/r/20240117-b4-zswap-lock-optimize-v2-0-b5cc55479090@bytedance.com
Link: https://lkml.kernel.org/r/20240117-b4-zswap-lock-optimize-v2-1-b5cc55479090@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Chris Li <chriscli@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 10:24:39 -08:00
arch mm: convert mm_counter() to take a folio 2024-02-21 16:00:03 -08:00
block
certs
crypto
Documentation Kbuild fixes for v6.8 (2nd) 2024-02-18 10:09:25 -08:00
drivers s390/mm: implement MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers 2024-02-21 16:00:02 -08:00
fs userfaultfd: fix return error if mmap_changing is non-zero in MOVE ioctl 2024-02-22 10:24:38 -08:00
include mm/zswap: make sure each swapfile always have zswap rb-tree 2024-02-22 10:24:39 -08:00
init update workarounds for gcc "asm goto" issue 2024-02-15 11:14:33 -08:00
io_uring io_uring/net: fix multishot accept overflow handling 2024-02-14 18:30:19 -07:00
ipc
kernel mm: convert mm_counter_file() to take a folio 2024-02-21 16:00:04 -08:00
lib maple_tree: avoid duplicate variable init in mast_spanning_rebalance() 2024-02-22 10:24:39 -08:00
LICENSES
mm mm/zswap: make sure each swapfile always have zswap rb-tree 2024-02-22 10:24:39 -08:00
net Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -08:00
rust
samples
scripts scripts/gdb/vmalloc: fix vmallocinfo error 2024-02-21 16:00:02 -08:00
security lsm/stable-6.8 PR 20240215 2024-02-16 07:58:43 -08:00
sound ALSA: usb-audio: More relaxed check of MIDI jack names 2024-02-15 16:56:05 +01:00
tools selftests: mm: perform some system cleanup before using hugepages 2024-02-22 10:24:39 -08:00
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.mailmap MAINTAINERS: mailmap: update Shakeel's email address 2024-02-20 14:20:50 -08:00
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MAINTAINERS MAINTAINERS: mailmap: update Shakeel's email address 2024-02-20 14:20:50 -08:00
Makefile Linux 6.8-rc5 2024-02-18 12:56:25 -08:00
README

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.