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Tue, 13 Apr 2021 06:12:19 +0000 IronPort-SDR: 1+VTxyh5hXKkICmQAzcJNu9PQQhRHQhzZkga306XZDwdSu8oSB4ckzVzZ5SZoPkdPAXpdvrb7M hXDkS/1wPquw== X-IronPort-AV: E=McAfee;i="6200,9189,9952"; a="193906917" X-IronPort-AV: E=Sophos;i="5.82,218,1613462400"; d="scan'208";a="193906917" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Apr 2021 23:12:14 -0700 IronPort-SDR: 8BmBhJK0aFEb0A6dirM7HWR6n/PN+I26Mj1zqT9+2QxNRGj+RRG97Us1wmQJfhse4G4wMbbI5k Ju5YeNZe0CTQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,218,1613462400"; d="scan'208";a="450267331" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.54.74.11]) by FMSMGA003.fm.intel.com with ESMTP; 12 Apr 2021 23:12:13 -0700 Received: by tassilo.localdomain (Postfix, from userid 1000) id D426B301AA9; Mon, 12 Apr 2021 23:12:13 -0700 (PDT) From: Andi Kleen To: Alex Kogan 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 v14 4/6] locking/qspinlock: Introduce starvation avoidance into CNA References: <20210401153156.1165900-1-alex.kogan@oracle.com> <20210401153156.1165900-5-alex.kogan@oracle.com> <87mtu2vhzz.fsf@linux.intel.com> Date: Mon, 12 Apr 2021 23:12:13 -0700 In-Reply-To: <87mtu2vhzz.fsf@linux.intel.com> (Andi Kleen's message of "Mon, 12 Apr 2021 23:03:12 -0700") Message-ID: <87im4qvhky.fsf@linux.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210412_231218_931719_680F3411 X-CRM114-Status: GOOD ( 12.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Andi Kleen writes: > Alex Kogan writes: >> >> + numa_spinlock_threshold= [NUMA, PV_OPS] >> + Set the time threshold in milliseconds for the >> + number of intra-node lock hand-offs before the >> + NUMA-aware spinlock is forced to be passed to >> + a thread on another NUMA node. Valid values >> + are in the [1..100] range. Smaller values result >> + in a more fair, but less performant spinlock, >> + and vice versa. The default value is 10. > > ms granularity seems very coarse grained for this. Surely > at some point of spinning you can afford a ktime_get? But ok. Actually thinking about it more using jiffies is likely broken anyways because if the interrupts are disabled and the CPU is running the main timer interrupts they won't increase. cpu_clock (better than ktime_get) or sched_clock would work. -Andi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel