linux-kernel - Re: [PATCH v10 2/5] sched: CGroup tagging interface for core scheduling

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Message-ID: <94f43bb6-501c-2851-de32-6f4356b4a480@oracle.com>
Date:   Wed, 24 Feb 2021 08:52:11 -0500
From:   chris hyser <chris.hyser@...cle.com>
To:     Josh Don <joshdon@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>, mingo@...nel.org,
        torvalds@...ux-foundation.org, fweisbec@...il.com,
        Kees Cook <keescook@...omium.org>,
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        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH v10 2/5] sched: CGroup tagging interface for core
 scheduling

On 2/24/21 8:02 AM, Chris Hyser wrote:

>> However, it means that overall throughput of your binary is cut in
>> ~half, since none of the threads can share a core. Note that I never
>> saw an indefinite deadlock, just ~2x runtime for your binary vs th > control. I've verified that both a) manually 
>> hardcoding all threads to
>> be able to share regardless of cookie, and b) using a machine with 6
>> cores instead of 2, both allow your binary to complete in the same
>> amount of time as without the new API.
> 
> This was on a 24 core box. When I run the test, I definitely hangs. I'll answer your other email as wwll.


I just want to clarify. The test completes in secs normally. When I run this on the 24 core box from the console, other 
ssh connections immediately freeze. The console is frozen. You can't ping the box and it has stayed that way for up to 
1/2 hour before I reset it. I'm trying to get some kind of stack trace to see what it is doing. To the extent that I've 
been able to trace it or print it, the "next code" always seems to be __sched_core_update_cookie(p);

-chrish