linux-kernel - Re: [PATCH] intel_idle: add CPUIDLE_FLAG_IRQ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <22D82855-259A-425A-B401-2F51EEC3C746@nutanix.com>
Date:   Fri, 10 Nov 2023 20:00:38 +0000
From:   Jon Kohler <jon@...anix.com>
To:     Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
CC:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] intel_idle: add CPUIDLE_FLAG_IRQ_ENABLE to SPR C1 and C1E



> On Jul 1, 2022, at 10:06 AM, Jon Kohler <jon@...anix.com> wrote:
> 
> 
> 
>> On Jul 1, 2022, at 9:30 AM, Artem Bityutskiy <artem.bityutskiy@...ux.intel.com> wrote:
>> 
>> Hi Jon,
>> 
>> On Thu, 2022-06-30 at 15:43 -0400, Jon Kohler wrote:
>>> Add CPUIDLE_FLAG_IRQ_ENABLE to spr_cstates C1 and C1E, which will
>>> allow local IRQs to be enabled during fast idle transitions on SPR.
>> 
>> Did you have a chance to measure this? When I was doing this for ICX and CLX, I
>> was using cyclictest and wult for measuring IRQ latency.
>> 
>> I was planning to do this for SPR as well.
> 
> We have the ‘before’ baseline from wult, and realized after doing it that
> IRQ_ENABLE config wasn’t set. I’ve provided this patch to our internal
> team working on SPR enablement to get another wult run in next week.
> 
> That said, if you’ve got access to an SPR system setup as well, we’d
> certainly appreciate a second set of eyes. This is the first generation
> of enablement for a new platform that we’ve done where wult has been
> on the ‘checklist’ so to speak, so we don’t have as much ’stick time’
> on it as someone like yourself would :) 
> 
>> 
>>> Note: Enabling this for both C1 and C1E is slightly different than
>>> the approach for SKX/ICX, where CPUIDLE_FLAG_IRQ_ENABLE is only
>>> enabled on C1; however, given that SPR target/exit latency is 1/1
>>> for c1 and 2/4 for C1E, respectively, which is slower than C1
>>> for SKX, it seems prudent to now enable it on both states.
>> 
>> I was also going to measure this for C1E.
>> 
>> Could we please hold on this a bit - I'd like to measure this before we merge
>> it.
> 
> Yea no problem, happy to get help and a second set of eyes on this.
> 
> Thanks - Jon

Hey Artem,
Coming back around on this, I realized this fell through the cracks. I was wondering
if you happened to run through this testing on your side already as part of other
efforts? 

If not, I’ll see if we can get it spun back up on our side. 

Thanks,
Jon

> 
>> 
>> Artem.