Mailinglist Archive: opensuse-factory (439 mails)

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Re: [opensuse-factory] Huge single-core performance loss with spectre v2 mitigation enabled (it's the default)
On 4/10/19 1:01 PM, Lars Marowsky-Bree wrote:
On 2019-04-10T12:31:31, Michael Pujos <pujos.michael@xxxxxxxxx> wrote:

spectre_v2=retpoline,generic should be the default in my opinion. If good
guys at Fedora (and other distros) are using it, so can openSUSE.
Unless the people in charge want to murder single-core performance on
people's computers and lament why it always comes last in Phoronix (and
other) benchmarks.
It probably makes sense to discuss why "we" choose these settings vs
what Fedora picked. I'm not clear that, when it comes to security, we
should automatically go with those just because Fedora did and they
are faster.

Maybe, but the defaults should not incur a 20% performance loss.
Especially since there is an alternate spectre v2 mitigation.
Maybe such loss is tolerable for datacenters as they can throw more hardware at it, but not on most personal computers.
I really hope the defaults will be changed to something more sensible.
I vaguely remember a post by Linus Torvalds stating that a mitigation that has a huge performance loss should be turned off by default.
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