[kwlug-disc] Meltown fix for Linux kernel

[L.D. Paniak]

Looks like you will see substantial performance impact for I/O-heavy
workloads (especially synthetic ones):

https://www.phoronix.com/scan.php?page=news_item&px=KPTI-Retpoline-Combined-Ubuntu

The Apache server numbers are especially notable.


On 01/09/2018 07:18 PM, doug moen wrote:
> According to what I read, the performance impact occurs if you are
> hammering the kernel with a lot of system calls. Eg, a server that is
> performing a lot of I/o.
>
> On Tuesday, 9 January 2018, Khalid Baheyeldin <kb at 2bits.com
> <mailto:kb at 2bits.com>> wrote:
>
>     I just received the email for the meltdown patch for Ubuntu Linux.
>
>     CVE-2017-5754
>
>     There are two concerns:
>
>     1. Performance impact.
>
>     2. This comment in the email:
>
>     "ATTENTION: Due to an unavoidable ABI change the kernel updates have
>     been given a new version number, which requires you to recompile and
>     reinstall all third party kernel modules you might have installed.
>     Unless you manually uninstalled the standard kernel metapackages
>     (e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
>     linux-powerpc), a standard system upgrade will automatically perform
>     this as well."
>
>     Anyone updated to this fix yet?
>     Any noticeable negative impact on performance?
>
>     -- 
>     Khalid M. Baheyeldin
>     2bits.com <http://2bits.com>, Inc.
>     Fast Reliable Drupal
>     Drupal optimization, development, customization and consulting.
>     Simplicity is prerequisite for reliability. --  Edsger W.Dijkstra
>     Simplicity is the ultimate sophistication. --   Leonardo da Vinci
>     For every complex problem, there is an answer that is clear,
>     simple, and wrong." -- H.L. Mencken
>
>
>
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