From: Rahul Rameshbabu <rrameshbabu@nvidia.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Gal Pressman <gal@nvidia.com>
Subject: Re: [PATCH] powerpc/64s: Increase default stack size to 32KB
Date: Wed, 14 Feb 2024 12:47:39 -0800 [thread overview]
Message-ID: <87ttmau5mg.fsf@nvidia.com> (raw)
In-Reply-To: <20231215124449.317597-1-mpe@ellerman.id.au>
On Fri, 15 Dec, 2023 23:44:49 +1100 Michael Ellerman <mpe@ellerman.id.au> wrote:
> There are reports of kernels crashing due to stack overflow while
> running OpenShift (Kubernetes). The primary contributor to the stack
> usage seems to be openvswitch, which is used by OVN-Kubernetes (based on
> OVN (Open Virtual Network)), but NFS also contributes in some stack
> traces.
>
> There may be some opportunities to reduce stack usage in the openvswitch
> code, but doing so potentially require tradeoffs vs performance, and
> also requires testing across architectures.
>
> Looking at stack usage across the kernel (using -fstack-usage), shows
> that ppc64le stack frames are on average 50-100% larger than the
> equivalent function built for x86-64. Which is not surprising given the
> minimum stack frame size is 32 bytes on ppc64le vs 16 bytes on x86-64.
>
> So increase the default stack size to 32KB for the modern 64-bit Book3S
> platforms, ie. pseries (virtualised) and powernv (bare metal). That
> leaves the older systems like G5s, and the AmigaOne (pasemi) with a 16KB
> stack which should be sufficient on those machines.
>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---
We noticed this change is causing assembler issues for us when building
the kernel.
make ARCH=powerpc KERNELRELEASE=6.8.0-rc2_for_upstream_debug_2024_02_06_20_01 KBUILD_BUILD_VERSION=1
arch/powerpc/kernel/switch.S: Assembler messages:
arch/powerpc/kernel/switch.S:249: Error: operand out of range (0x000000000000fe50 is not between 0xffffffffffff8000 and 0x0000000000007fff)
make[6]: *** [scripts/Makefile.build:361: arch/powerpc/kernel/switch.o] Error 1
make[5]: *** [scripts/Makefile.build:481: arch/powerpc/kernel] Error 2
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [scripts/Makefile.build:481: arch/powerpc] Error 2
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [Makefile:1921: .] Error 2
The issue lies with the do_switch_64 macro.
--
Thanks,
Rahul Rameshbabu
next prev parent reply other threads:[~2024-02-14 20:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-15 12:44 [PATCH] powerpc/64s: Increase default stack size to 32KB Michael Ellerman
2023-12-19 12:32 ` Michael Ellerman
2024-02-14 20:47 ` Rahul Rameshbabu [this message]
2024-02-14 21:56 ` Michael Ellerman
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