linux-kernel - Re: [PATCH v4] membarrier: expedited private command

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Message-ID: <20170731192344.GA79955@dhcp-172-20-173-153.dhcp.thefacebook.com>
Date:   Mon, 31 Jul 2017 12:23:44 -0700
From:   Dave Watson <davejwatson@...com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        <linux-kernel@...r.kernel.org>, Boqun Feng <boqun.feng@...il.com>,
        Andrew Hunter <ahh@...gle.com>,
        Maged Michael <maged.michael@...il.com>, <gromer@...gle.com>,
        Avi Kivity <avi@...lladb.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v4] membarrier: expedited private command

On 07/28/17 04:40 PM, Mathieu Desnoyers wrote:
> Implement MEMBARRIER_CMD_PRIVATE_EXPEDITED with IPIs using cpumask built
> from all runqueues for which current thread's mm is the same as the
> thread calling sys_membarrier. It executes faster than the non-expedited
> variant (no blocking). It also works on NOHZ_FULL configurations.

I tested this with our hazard pointer use case on x86_64, and it seems
to work great.  We don't currently have any uses needing SHARED.

Tested-by: Dave Watson <davejwatson@...com>

Thanks!

https://github.com/facebook/folly/blob/master/folly/experimental/hazptr/hazptr-impl.h#L555
https://github.com/facebook/folly/blob/master/folly/experimental/AsymmetricMemoryBarrier.cpp#L86