Re: [PATCH v5 00/18] locking/rwsem: Rwsem rearchitecture part 2

Ingo Molnar
2019-04-19T18:34:56Z

* Ingo Molnar <mingo@kernel.org> wrote:

>
> * Waiman Long <longman@redhat.com> wrote:
>
> > On 04/18/2019 07:46 PM, Waiman Long wrote:
> > > v5:
> > > - Drop v4 patch 1 as it is merged into tip's locking/core branch.
> > > - Integrate the 2 followup patches into the series. The first
> > > follow-up patch is broken into 2 pieces. The first piece comes in
> > > before the "Enable readers spinning on writer" and the 2nd piece
> > > is merged into the "Enable time-based spinning on reader-owned
> > > rwsem" patch. The 2nd followup patch is added after that.
> > > - Add a new patch to make all wake_up_q() calls after dropping
> > > wait_lock as suggested by PeterZ.
> > > - Incorporate numerouos suggestions by PeterZ and Davidlohr.
> >
> > This patchset is still being reviewed by Peter . The purpose of this
> > series is mainly to sync up the version that Peter has and the ones that
> > I am working on incorporating his feedback. Further changes may still be
> > needed.
> >
> > I run an overall performance test on this new patchset and present the
> > data in this cover letter. However, I haven't run performance tests for
> > individual patches. So the performance data listed in some of the
> > patches may be stale.
>
> Just for those who'd like to follow the scope of changes, find below the
> v4->v5 interdiff. v5 is now included in tip:WIP.locking/core, and also
> merged into tip:master. (But not propagated towards linux-next yet.)

Hm, I'm experiencing early boot hangs with v5, on defconfig-ish x86-64
kernels:

[ 0.153940] rcu: Hierarchical RCU implementation.
[ 0.154289] rcu: RCU restricting CPUs from NR_CPUS=128 to nr_cpu_ids=17.
[ 0.154829] rcu: RCU calculated value of scheduler-enlistment delay is 100 jiffies.
[ 0.155390] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=17

I bisected it back to the v5 version of this patch:

2fd5f60fa4c3: locking/rwsem: Merge owner into count on x86-64

I'm moving -tip back to -v4 meanwhile.

Thanks,

Ingo