linux-kernel - Re: [EXT] Re: [PATCH v4 00/13] "Task

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Date:   Thu, 23 Jul 2020 16:19:16 +0000
From:   Alex Belits <abelits@...vell.com>
To:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "peterz@...radead.org" <peterz@...radead.org>
CC:     "mingo@...nel.org" <mingo@...nel.org>,
        Prasun Kapoor <pkapoor@...vell.com>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "frederic@...nel.org" <frederic@...nel.org>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [EXT] Re: [PATCH v4 00/13] "Task_isolation" mode


On Thu, 2020-07-23 at 17:48 +0200, Peter Zijlstra wrote:
> On Thu, Jul 23, 2020 at 03:41:46PM +0000, Alex Belits wrote:
> > On Thu, 2020-07-23 at 16:29 +0200, Peter Zijlstra wrote:
> > > .
> > > 
> > > This.. as presented it is an absolutely unreviewable pile of
> > > junk. It
> > > presents code witout any coherent problem description and
> > > analysis.
> > > And
> > > the patches are not split sanely either.
> > 
> > There is a more complete and slightly outdated description in the
> > previous version of the patch at 
> > https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_lkml_07c25c246c55012981ec0296eee23e68c719333a.camel-40marvell.com_&d=DwIBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=1qgvOnXfk3ZHJA3p7RIb6NFqs4SPPDyPI_PcwNFp8KY&m=shk9a5FDwktOZysSbFIjxmgUg-IPyw2UkbVAHGBhNV0&s=FFZaj-KanwqEiXYCdjd96JOgP_GAOnanpkw6bBvNrK4&e= 
> 
> Not the point, you're mixing far too many things in one go. You also
> have the patches split like 'generic / arch-1 / arch-2' which is
> wrong
> per definition, as patches should be split per change and not care
> about
> sily boundaries.

This follows the original patch by Chris Metcalf. There is a reason for
that -- per-architecture changes are independent from each other and
affect not just code but functionality that was implemented per-
architecture. To support more architectures, it will be necessary to do
it separately for each, and mark them supported with
HAVE_ARCH_TASK_ISOLATION. Having only some architectures supported does
not break anything for the rest -- architectures that are not covered,
would not have this functionality.

> 
> Also, if you want generic entry code, there's patches for that here:
> 
>   
> https://urldefense.proofpoint.com/v2/url?u=https-3A__lkml.kernel.org_r_20200722215954.464281930-40linutronix.de&d=DwIBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=1qgvOnXfk3ZHJA3p7RIb6NFqs4SPPDyPI_PcwNFp8KY&m=shk9a5FDwktOZysSbFIjxmgUg-IPyw2UkbVAHGBhNV0&s=nZXIviY7rva31KvPgSVnTacwFNbsmkdW0LxSTfYSiqg&e=
>  
> 
> 

That looks useful. Why didn't Thomas Gleixner mention it in his
criticism of my approach if he already solved that exact problem, at
least for x86?

-- 
Alex