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Date:   Wed, 5 Jun 2019 13:16:46 -0700
From:   Linus Torvalds <>
To:     Jan Glauber <>
Cc:     Linux List Kernel Mailing <>,
        Catalin Marinas <>,
        Will Deacon <>,
        Linux ARM <>,
        Jayachandran Chandrasekharan Nair <>,
        Jan Glauber <>
Subject: Re: [PATCH] lockref: Limit number of cmpxchg loop retries

On Wed, Jun 5, 2019 at 6:49 AM Jan Glauber <> wrote:
> Add an upper bound to the loop to force the fallback to spinlocks
> after some time. A retry value of 100 should not impact any hardware
> that does not have this issue.
> With the retry limit the performance of an open-close testcase
> improved between 60-70% on ThunderX2.

Btw, did you do any kind of performance analysis across different
retry limit values?

I'm perfectly happy to just pick a random number and '100' looks fine
to me, so this is mainly out of curiosity.


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