From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rjfMZ3hCKzDr3c for ; Mon, 4 Jul 2016 17:50:50 +1000 (AEST) Message-ID: <1467618640.13965.3.camel@kernel.crashing.org> Subject: Re: powerpc/opal: Wake up kopald polling thread before waiting for events From: Benjamin Herrenschmidt To: Michael Ellerman , linuxppc-dev@lists.ozlabs.org Cc: mikey@neuling.org Date: Mon, 04 Jul 2016 17:50:40 +1000 In-Reply-To: <3rjc8Z6nDPz9sXx@ozlabs.org> References: <3rjc8Z6nDPz9sXx@ozlabs.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2016-07-04 at 16:11 +1000, Michael Ellerman wrote: > On Mon, 2016-04-07 at 04:51:44 UTC, Benjamin Herrenschmidt wrote: > > On some environments (prototype machines, some simulators, etc...) > > there is no functional interrupt source to signal completion, so > > we rely on the fairly slow OPAL heartbeat. > > > > In a number of cases, the calls complete very quickly or even > > immediately. We've observed that it helps a lot to wakeup the OPAL > > heartbeat thread before waiting for event in those cases, it will > > call OPAL immediately to collect completions for anything that > > finished fast enough. > > Any performance/jitter impact on normal systems? Not that I can think of. Cheers, Ben.