Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932817AbbKMQNu (ORCPT ); Fri, 13 Nov 2015 11:13:50 -0500 Received: from mail-ig0-f171.google.com ([209.85.213.171]:33749 "EHLO mail-ig0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932498AbbKMQNt (ORCPT ); Fri, 13 Nov 2015 11:13:49 -0500 Message-ID: <1447431225.5655.66.camel@gmail.com> Subject: Re: __i915_spin_request() sucks From: Mike Galbraith To: Jens Axboe Cc: Chris Wilson , Daniel Vetter , DRI Development , LKML Date: Fri, 13 Nov 2015 09:13:45 -0700 In-Reply-To: <20151113153629.GB8939@kernel.dk> References: <5644F850.2060803@kernel.dk> <5644F941.9090505@kernel.dk> <20151112221908.GA26194@nuc-i3427.alporthouse.com> <56451812.2050704@kernel.dk> <20151113091558.GN6247@nuc-i3427.alporthouse.com> <20151113153629.GB8939@kernel.dk> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1359 Lines: 42 On Fri, 2015-11-13 at 08:36 -0700, Jens Axboe wrote: > Previous patch was obvious pre-coffee crap, this should work for using > ktime to spin max 1usec. 1us seems a tad low. I doubt the little wooden gears and pulleys of my core2 Toshiba Satellite lappy can get one loop ground out in a usec :) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 5cf4a1998273..21192e55c33c 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1148,17 +1148,18 @@ static bool missed_irq(struct drm_i915_private *dev_priv, > > static int __i915_spin_request(struct drm_i915_gem_request *req) > { > - unsigned long timeout; > + ktime_t timeout; > > if (i915_gem_request_get_ring(req)->irq_refcount) > return -EBUSY; > > - timeout = jiffies + 1; > + timeout = ktime_get(); > + ktime_add_us(timeout, 1); > while (!need_resched()) { > if (i915_gem_request_completed(req, true)) > return 0; > > - if (time_after_eq(jiffies, timeout)) > + if (ktime_after(ktime_get(), timeout)) > break; > > cpu_relax_lowlatency(); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/