Re: [PATCH v2 00/14] Introducing TIF_NOTIFY_IPI flag
From: K Prateek Nayak <kprateek.nayak@amd.com>
Date: 2024-06-17 04:35:59
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Hello Russell, On 6/15/2024 7:56 PM, Russell King (Oracle) wrote:
On Thu, Jun 13, 2024 at 06:15:59PM +0000, K Prateek Nayak wrote:quoted
o Dropping the ARM results since I never got my hands on the ARM64 system I used in my last testing. If I do manage to get my hands on it again, I'll rerun the experiments and share the results on the thread. To test the case where TIF_NOTIFY_IPI is not enabled for a particular architecture, I applied the series only until Patch 3 and tested the same on my x86 machine with a WARN_ON_ONCE() in do_idle() to check if tif_notify_ipi() ever return true and then repeated the same with Patch 4 applied.Confused. ARM (32-bit) or ARM64? You patch 32-bit ARM, but you don't touch 64-bit Arm. "ARM" on its own in the context above to me suggests 32-bit, since you refer to ARM64 later.
In my first RFC posting, I had shared the results for ipistorm on an ARM64 server [1]. Vincent and Linus Walleij brought to my attention that ARM32 and ARM64 do not share the thread info flags and I probably saw a one-off behavior during my testing. Since then, it has been slightly challenging to get my hands on that machine again in a stable condition to see if there was any scenario that I might have missed but I tried a bunch of things on my x86 machine to confirm that an arch that does not define the TIF_NOTIFY_IPI would not hit these changes. Rest assured, Patch 5 is for ARM32 machines that currently define TIF_POLLING_NRFLAG [1] https://lore.kernel.org/lkml/20240220171457.703-6-kprateek.nayak@amd.com/ (local) -- Thanks and Regards, Prateek