linux-kernel - Re: [PATCH-tip v2 00/12] locking/rwsem: Rwsem rearchitecture part 2

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Date:   Wed, 10 Apr 2019 08:38:24 -0400
From:   Waiman Long <longman@...hat.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Will Deacon <will.deacon@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: [PATCH-tip v2 00/12] locking/rwsem: Rwsem rearchitecture part 2

On 04/10/2019 06:00 AM, Ingo Molnar wrote:
> * Waiman Long <longman@...hat.com> wrote:
>
>>    # of Threads   Before Patch      After Patch
>>    ------------   ------------      -----------
>>         2            1,179             9,436
>>         4            1,505             8,268
>>         8              721             7,041
>>        16              575             7,652
>>        32               70             2,189
>>        64               39               534
>>
>> Waiman Long (12):
>>   locking/rwsem: Implement a new locking scheme
>>   locking/rwsem: Implement lock handoff to prevent lock starvation
>>   locking/rwsem: Remove rwsem_wake() wakeup optimization
>>   locking/rwsem: Make rwsem_spin_on_owner() return owner state
>>   locking/rwsem: Ensure an RT task will not spin on reader
>>   locking/rwsem: Wake up almost all readers in wait queue
>>   locking/rwsem: Enable readers spinning on writer
>>   locking/rwsem: Enable time-based spinning on reader-owned rwsem
>>   locking/rwsem: Add more rwsem owner access helpers
>>   locking/rwsem: Guard against making count negative
>>   locking/rwsem: Merge owner into count on x86-64
>>   locking/rwsem: Remove redundant computation of writer lock word
>>
>>  kernel/locking/lock_events_list.h |   4 +
>>  kernel/locking/rwsem-xadd.c       | 635 +++++++++++++++++++-----------
>>  kernel/locking/rwsem.c            |   3 +-
>>  kernel/locking/rwsem.h            | 290 +++++++++++---
>>  4 files changed, 647 insertions(+), 285 deletions(-)
> Looks very nice!
>
> With both sets of patches applied they pass all x86 tests, but there's 
> cross-build failures on powerpc32, sparc32 and UML:
>
>    kernel/locking/rwsem.h:333:34: error: 'struct rw_semaphore' has no member named 'owner'
>
> Could you please send a delta patch against tip:WIP.locking/core, which 
> is the work-in-progress tree? I'll backmerge the delta patch (and any 
> other updates you might have meanwhil) to the one that introduces the 
> breakage.
>
> Thanks,
>
> 	Ingo

Sure. I will look into that and fix failures.

Thanks,
Longman