Messages in this thread | | | Subject | Re: [tip: locking/urgent] locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling | From | Waiman Long <> | Date | Wed, 17 Mar 2021 10:10:16 -0400 |
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On 3/17/21 9:55 AM, Peter Zijlstra wrote: > On Wed, Mar 17, 2021 at 09:43:20AM -0400, Waiman Long wrote: > >> Using gcc 8.4.1, the generated __mutex_lock function has the same size (with >> last instruction at offset +5179) with or without this patch. Well, you can >> say that this patch is an no-op wrt generated code. > OK, then GCC has gotten better. Because back then I tried really hard > but it wouldn't remove the if (ww_ctx) branches unless I had that extra > const bool argument. > I think ww_mutex was merged in 2013. That is almost 8 years ago. It could still be the case that older gcc compilers may not generate the right code. I will try the RHEL7 gcc compiler (4.8.5) to see how it fares.
Cheers, Longman
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