Re: [PATCH v3 2/2] modules/kmod: replace implementation with a semaphore

[Miroslav Benes]

On Thu, 13 Apr 2023, Luis Chamberlain wrote:

> Simplify the concurrency delimiter we use for kmod with the semaphore.
> I had used the kmod strategy to try to implement a similar concurrency
> delimiter for the kernel_read*() calls from the finit_module() path
> so to reduce vmalloc() memory pressure. That effort didn't provide yet
> conclusive results, but one thing that became clear is we can use
> the suggested alternative solution with semaphores which Linus hinted
> at instead of using the atomic / wait strategy.
> 
> I've stress tested this with kmod test 0008:
> 
> time /data/linux-next/tools/testing/selftests/kmod/kmod.sh -t 0008
> 
> And I get only a *slight* delay. That delay however is small, a few
> seconds for a full test loop run that runs 150 times, for about ~30-40
> seconds. The small delay is worth the simplfication IMHO.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>

Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>

M