From patchwork Tue Nov 12 09:28:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11238889 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B0F6514ED for ; Tue, 12 Nov 2019 09:29:15 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 98E2821925 for ; Tue, 12 Nov 2019 09:29:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98E2821925 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0F7696EA9B; Tue, 12 Nov 2019 09:29:15 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 26B1A89E9B for ; Tue, 12 Nov 2019 09:29:12 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 19170021-1500050 for multiple; Tue, 12 Nov 2019 09:28:58 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 12 Nov 2019 09:28:43 +0000 Message-Id: <20191112092854.869-16-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191112092854.869-1-chris@chris-wilson.co.uk> References: <20191112092854.869-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 16/27] drm/i915/gt: Expose timeslice duration to sysfs X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Execlists uses a scheduling quantum (a timeslice) to alternate execution between ready-to-run contexts of equal priority. This ensures that all users (though only if they of equal importance) have the opportunity to run and prevents livelocks where contexts may have implicit ordering due to userspace semaphores. The timeslicing mechanism can be compiled out with ./scripts/config --set-val DRM_I915_TIMESLICE_DURATION 0 The timeslice duration can be adjusted per-engine using, /sys/class/drm/card?/engine/*/timeslice_duration_ms Signed-off-by: Chris Wilson Cc: Joonas Lahtinen --- drivers/gpu/drm/i915/Kconfig.profile | 3 ++ drivers/gpu/drm/i915/gt/intel_engine_sysfs.c | 46 ++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/drivers/gpu/drm/i915/Kconfig.profile b/drivers/gpu/drm/i915/Kconfig.profile index 1799537a3228..b87c8f485a24 100644 --- a/drivers/gpu/drm/i915/Kconfig.profile +++ b/drivers/gpu/drm/i915/Kconfig.profile @@ -73,4 +73,7 @@ config DRM_I915_TIMESLICE_DURATION is scheduled for execution for the timeslice duration, before switching to the next context. + This is adjustable via + /sys/class/drm/card?/engine/*/timeslice_duration_ms + May be 0 to disable timeslicing. diff --git a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c index abddd8d0f9ae..b1bd768b13d7 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_sysfs.c @@ -142,6 +142,48 @@ all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) static struct kobj_attribute all_caps_attr = __ATTR(known_capabilities, 0444, all_caps_show, NULL); +static ssize_t +timeslice_store(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct intel_engine_cs *engine = kobj_to_engine(kobj); + unsigned long long duration; + int err; + + /* + * Execlists uses a scheduling quantum (a timeslice) to alternate + * execution between ready-to-run contexts of equal priority. This + * ensures that all users (though only if they of equal importance) + * have the opportunity to run and prevents livelocks where contexts + * may have implicit ordering due to userspace semaphores. + */ + + err = kstrtoull(buf, 0, &duration); + if (err) + return err; + + if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT)) + return -EINVAL; + + WRITE_ONCE(engine->props.timeslice_duration_ms, duration); + + if (execlists_active(&engine->execlists)) + set_timer_ms(&engine->execlists.timer, duration); + + return count; +} + +static ssize_t +timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) +{ + struct intel_engine_cs *engine = kobj_to_engine(kobj); + + return sprintf(buf, "%lu\n", engine->props.timeslice_duration_ms); +} + +static struct kobj_attribute timeslice_duration_attr = +__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store); + static void kobj_engine_release(struct kobject *kobj) { kfree(kobj); @@ -206,6 +248,10 @@ void intel_engines_add_sysfs(struct drm_i915_private *i915) if (sysfs_create_files(kobj, files)) goto err_object; + if (intel_engine_has_timeslices(engine) && + sysfs_create_file(kobj, ×lice_duration_attr.attr)) + goto err_engine; + if (0) { err_object: kobject_put(kobj);