[lkml]   [2016]   [Oct]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] x86/AMD: Apply erratum 688 on machines without a BIOS fix
On Mon, Oct 24, 2016 at 02:38:06PM +0300, wrote:
> The patch is not equivalent to the original. As a result it behaves
> differently. To be specific, using dmesg I get the expected value from the
> affected MSR with the original patch. With the latest patch, patching of the
> MSR occurs after dmesg prints the MSR information. That is why I thought it
> did nothing.

Gah, that "show_msr" is crap - it gets issued too early and we can -
and we do - set MSRs later too. Oh and it prints only the BSP. I should
probably rip it out - there's msr-tools for that which is much better.

> rdmsr --all 0xc0011021 returns the expected results on all CPUs with both
> patches. I have the impression that the system boots slower because the fix
> is applied later compared to the original patch.

Could be - setting those bits 3 in 14 in that MSR is probably disabling
some hw features which may impact performance.

> Could you please use perf and tell me what values do you get at perf
> branch-misses right after boot on your ON-B0 box? Launching firefox with
> only one tab gives you similar numbers?

Sure, give me the exact command you're executing so that I can do it here.

> If you need anything more, feel free to ask.

Out of pure interest: do you remember how exactly you did reproduce this



ECO tip #101: Trim your mails when you reply.

 \ /
  Last update: 2016-10-24 14:36    [W:0.059 / U:2.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site