From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
Mark Rutland <mark.rutland@arm.com>,
ndesaulniers@google.com, linux-kernel@vger.kernel.org,
Nicholas Piggin <npiggin@gmail.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Josh Poimboeuf <jpoimboe@kernel.org>
Subject: Re: [PATCH] powerpc/smp: Dynamically build powerpc topology
Date: Tue, 5 Sep 2023 00:10:04 +0200 [thread overview]
Message-ID: <20230904221004.GB2568@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20230830122614.73067-1-srikar@linux.vnet.ibm.com>
On Wed, Aug 30, 2023 at 05:56:14PM +0530, Srikar Dronamraju wrote:
> Currently there are four powerpc specific sched topologies. These are
> all statically defined. However not all these topologies are used by
> all powerpc systems.
>
> To avoid unnecessary degenerations by the scheduler , masks and flags
> are compared. However if the sched topologies are build dynamically then
> the code is simpler and there are greater chances of avoiding
> degenerations.
>
> Even x86 builds its sched topologies dynamically and new changes are
> very similar to the way x86 is building its topologies.
You're not stating it explicitly, but you're doing this as a performance
optimization, right? The x86 thing didn't particularly care about
avoiding degenerate topologies -- it's just that the fixed tables method
grew unwieldy due to combinatorics.
And how does this patch relate to the other series touching this?
powerpc/smp: Shared processor sched optimizations
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
ndesaulniers@google.com, Nathan Lynch <nathanl@linux.ibm.com>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/smp: Dynamically build powerpc topology
Date: Tue, 5 Sep 2023 00:10:04 +0200 [thread overview]
Message-ID: <20230904221004.GB2568@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20230830122614.73067-1-srikar@linux.vnet.ibm.com>
On Wed, Aug 30, 2023 at 05:56:14PM +0530, Srikar Dronamraju wrote:
> Currently there are four powerpc specific sched topologies. These are
> all statically defined. However not all these topologies are used by
> all powerpc systems.
>
> To avoid unnecessary degenerations by the scheduler , masks and flags
> are compared. However if the sched topologies are build dynamically then
> the code is simpler and there are greater chances of avoiding
> degenerations.
>
> Even x86 builds its sched topologies dynamically and new changes are
> very similar to the way x86 is building its topologies.
You're not stating it explicitly, but you're doing this as a performance
optimization, right? The x86 thing didn't particularly care about
avoiding degenerate topologies -- it's just that the fixed tables method
grew unwieldy due to combinatorics.
And how does this patch relate to the other series touching this?
powerpc/smp: Shared processor sched optimizations
next prev parent reply other threads:[~2023-09-04 22:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 12:26 [PATCH] powerpc/smp: Dynamically build powerpc topology Srikar Dronamraju
2023-08-30 12:26 ` Srikar Dronamraju
2023-09-04 22:10 ` Peter Zijlstra [this message]
2023-09-04 22:10 ` Peter Zijlstra
2023-09-05 5:37 ` Srikar Dronamraju
2023-09-05 5:37 ` Srikar Dronamraju
2023-10-20 12:10 ` Michael Ellerman
2023-10-20 12:10 ` Michael Ellerman
2023-10-20 13:21 ` Srikar Dronamraju
2023-10-20 13:21 ` Srikar Dronamraju
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230904221004.GB2568@noisy.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=jpoimboe@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mark.rutland@arm.com \
--cc=nathanl@linux.ibm.com \
--cc=ndesaulniers@google.com \
--cc=npiggin@gmail.com \
--cc=srikar@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.