From: Davidlohr Bueso <dave@stgolabs.net>
To: Alex Kogan <alex.kogan@oracle.com>
Cc: linux@armlinux.org.uk, peterz@infradead.org, mingo@redhat.com,
will.deacon@arm.com, arnd@arndb.de, longman@redhat.com,
linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de,
hpa@zytor.com, x86@kernel.org, guohanjun@huawei.com,
jglauber@marvell.com, steven.sistare@oracle.com,
daniel.m.jordan@oracle.com, dave.dice@oracle.com
Subject: Re: [PATCH v15 3/6] locking/qspinlock: Introduce CNA into the slow path of qspinlock
Date: Wed, 22 Sep 2021 12:25:28 -0700 [thread overview]
Message-ID: <20210922192528.ob22pu54oeqsoeno@offworld> (raw)
In-Reply-To: <20210514200743.3026725-4-alex.kogan@oracle.com>
On Fri, 14 May 2021, Alex Kogan wrote:
>diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>index a816935d23d4..94d35507560c 100644
>--- a/Documentation/admin-guide/kernel-parameters.txt
>+++ b/Documentation/admin-guide/kernel-parameters.txt
>@@ -3515,6 +3515,16 @@
> NUMA balancing.
> Allowed values are enable and disable
>
>+ numa_spinlock= [NUMA, PV_OPS] Select the NUMA-aware variant
>+ of spinlock. The options are:
>+ auto - Enable this variant if running on a multi-node
>+ machine in native environment.
>+ on - Unconditionally enable this variant.
Is there any reason why the user would explicitly pass the on option
when the auto thing already does the multi-node check? Perhaps strange
numa topologies? Otherwise I would say it's not needed and the fewer
options we give the user for low level locking the better.
>+ off - Unconditionally disable this variant.
>+
>+ Not specifying this option is equivalent to
>+ numa_spinlock=auto.
>+
> numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
> 'node', 'default' can be specified
> This can be set from sysctl after boot.
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>index 0045e1b44190..819c3dad8afc 100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -1564,6 +1564,26 @@ config NUMA
>
> Otherwise, you should say N.
>
>+config NUMA_AWARE_SPINLOCKS
>+ bool "Numa-aware spinlocks"
>+ depends on NUMA
>+ depends on QUEUED_SPINLOCKS
>+ depends on 64BIT
>+ # For now, we depend on PARAVIRT_SPINLOCKS to make the patching work.
>+ # This is awkward, but hopefully would be resolved once static_call()
>+ # is available.
>+ depends on PARAVIRT_SPINLOCKS
We now have static_call() - see 9183c3f9ed7.
>+ default y
>+ help
>+ Introduce NUMA (Non Uniform Memory Access) awareness into
>+ the slow path of spinlocks.
>+
>+ In this variant of qspinlock, the kernel will try to keep the lock
>+ on the same node, thus reducing the number of remote cache misses,
>+ while trading some of the short term fairness for better performance.
>+
>+ Say N if you want absolute first come first serve fairness.
This would also need a depends on !PREEMPT_RT, no? Raw spinlocks really want
the determinism.
Thanks,
Davidlohr
next prev parent reply other threads:[~2021-09-22 19:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-14 20:07 [PATCH v15 0/6] Add NUMA-awareness to qspinlock Alex Kogan
2021-05-14 20:07 ` [PATCH v15 1/6] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan
2021-05-14 20:07 ` [PATCH v15 2/6] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2021-05-14 20:07 ` [PATCH v15 3/6] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2021-09-22 19:25 ` Davidlohr Bueso [this message]
2021-09-22 19:52 ` Waiman Long
2023-08-04 1:49 ` Guo Ren
2021-09-30 10:05 ` Barry Song
2023-08-02 23:14 ` Guo Ren
2023-08-03 8:50 ` Peter Zijlstra
2023-08-03 10:28 ` Guo Ren
2023-08-03 11:56 ` Peter Zijlstra
2023-08-04 1:33 ` Guo Ren
2023-08-04 1:38 ` Guo Ren
2023-08-04 8:25 ` Peter Zijlstra
2023-08-04 14:17 ` Guo Ren
2023-08-04 18:23 ` Peter Zijlstra
2023-08-05 0:19 ` Guo Ren
2021-05-14 20:07 ` [PATCH v15 4/6] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2021-05-14 20:07 ` [PATCH v15 5/6] locking/qspinlock: Avoid moving certain threads between waiting queues in CNA Alex Kogan
2021-05-14 20:07 ` [PATCH v15 6/6] locking/qspinlock: Introduce the shuffle reduction optimization into CNA Alex Kogan
2021-09-30 9:44 ` [PATCH v15 0/6] Add NUMA-awareness to qspinlock Barry Song
2021-09-30 16:58 ` Waiman Long
2021-09-30 22:57 ` Barry Song
2021-09-30 23:51 ` Alex Kogan
2021-12-13 20:37 ` Alex Kogan
2021-12-15 15:13 ` Alex Kogan
2022-04-11 17:09 ` Alex Kogan
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