linux-kernel - Re: [PATCH v2 8/8] powerpc: Enable Generic Entry/Exit for syscalls.

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Message-ID: <aT7jvN1u8P7XxQIW@gate>
Date: Sun, 14 Dec 2025 10:20:12 -0600
From: Segher Boessenkool <segher@...nel.crashing.org>
To: Mukesh Kumar Chaurasiya <mkchauras@...ux.ibm.com>
Cc: maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu, oleg@...hat.com, kees@...nel.org,
        luto@...capital.net, wad@...omium.org, mchauras@...ux.ibm.com,
        thuth@...hat.com, sshegde@...ux.ibm.com, charlie@...osinc.com,
        macro@...am.me.uk, akpm@...ux-foundation.org, ldv@...ace.io,
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        kan.liang@...ux.intel.com, mingo@...nel.org,
        atrajeev@...ux.vnet.ibm.com, mark.barnett@....com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 8/8] powerpc: Enable Generic Entry/Exit for syscalls.

Hi!

On Sun, Dec 14, 2025 at 06:32:44PM +0530, Mukesh Kumar Chaurasiya wrote:
> 
> | Test            | With Patch | Without Patch | % Change |
> | --------------- | ---------- | ------------- | -------- |
> | fork usec/op    | 833.986    | 814.809       | +2.35%   |

What causes this regression, did you investigate?  Maybe there is
something simple you can do to avoid this degradation :-)  All other
numbers look just fine :-)

> | Test            | With Patch | Without Patch | % Change |
> | --------------- | ---------- | ------------- | -------- |
> | fork ops/sec    | 1,199      | 1,227         | -2.28%   |

(Same thing seen from another side)


Segher