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Linux's vmalloc Seeing "Large Performance Benefits" With 5.2 Kernel Changes

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  • Linux's vmalloc Seeing "Large Performance Benefits" With 5.2 Kernel Changes

    Phoronix: Linux's vmalloc Seeing "Large Performance Benefits" With 5.2 Kernel Changes

    On top of all the changes queued for Linux 5.2 is an interesting last-minute performance improvement for the vmalloc code...

    http://www.phoronix.com/scan.php?pag...oc-Performance

  • GreenReaper
    replied
    Originally posted by tajjada View Post
    AFAIK ZFS is a heavy user of vmalloc, because it was ported from Solaris and using virtual memory in kernelspace is much more popular there than in Linux. Too bad ZFS is slow af on crippled 5.0+ kernels without patches to fix them.
    Well, here's your patch. What Linus taketh with one hand, he giveth back with another. Never said the performance had to be in the same place. ;-)

    Leave a comment:


  • tajjada
    replied
    AFAIK ZFS is a heavy user of vmalloc, because it was ported from Solaris and using virtual memory in kernelspace is much more popular there than in Linux. Too bad ZFS is slow af on crippled 5.0+ kernels without patches to fix them.

    Leave a comment:


  • zexelon
    replied
    This is obviously a huge travesty. Now all the SNES emulators will have to embed delay ops to counteract this performance improvement and keep the speed run players honest!

    Leave a comment:


  • nuetzel
    replied
    Originally posted by urezki View Post
    I gave a talk about this at LLC conference(https://lundlinuxcon.org) in Sweden. So if somebody is interested
    in you can find more details about it here: ftp://vps418301.ovh.net/incoming/Rew...nux_kernel.pdf

    --
    Vlad Rezki
    GREAT work! -Thank you.

    Leave a comment:


  • urezki
    replied
    I gave a talk about this at LLC conference(https://lundlinuxcon.org) in Sweden. So if somebody is interested
    in you can find more details about it here: ftp://vps418301.ovh.net/incoming/Rew...nux_kernel.pdf

    --
    Vlad Rezki

    Leave a comment:


  • Mikachu
    replied
    Originally posted by Widefox View Post
    Linus on vmalloc "There are basically no valid new uses of it. There's a few valid legacy users (I think the file descriptor array), and there are some drivers that use it (which is crap, but drivers are drivers), and it's _really_ valid only for modules. Nothing else." https://lwn.net/Articles/57800/
    This quote is 16 years old, a lot has changed since then. For example the kernel stack is now allocated via vmalloc[1], and every process that starts has one of these.
    [1]https://lwn.net/Articles/692208/

    Leave a comment:


  • reavertm
    replied
    Wow, never expected kernel to have linear lookup of anything in 2019...
    Last edited by reavertm; 05-20-2019, 12:45 PM.

    Leave a comment:


  • DoMiNeLa10
    replied
    Originally posted by Widefox View Post
    Linus on vmalloc "There are basically no valid new uses of it. There's a few valid legacy users (I think the file descriptor array), and there are some drivers that use it (which is crap, but drivers are drivers), and it's _really_ valid only for modules. Nothing else." https://lwn.net/Articles/57800/
    It's still a win, especially for mentioned embedded devices. It is unfortunate that there are plenty of crappy proprietary kernels, but they can still benefit from improvements to the mainline, this will apply especially to new devices where the manufacturer is still working on the kernel.

    Leave a comment:


  • Volta
    replied
    Originally posted by nuetzel View Post
    I think there was a much better one in the works for multi CPU/core systems...
    Yes, rwsem as far as I remember. Part of it is included in 5.2, but for full implementation we have to wait for 5.3.

    Leave a comment:

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