From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1477DC07E96 for ; Thu, 8 Jul 2021 17:38:23 +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 D29BE61879 for ; Thu, 8 Jul 2021 17:38:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D29BE61879 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4CF906E94C; Thu, 8 Jul 2021 17:38:13 +0000 (UTC) Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by gabe.freedesktop.org (Postfix) with ESMTPS id 20DFA6E94C for ; Thu, 8 Jul 2021 17:38:11 +0000 (UTC) Received: by mail-wr1-x42c.google.com with SMTP id i8so8486447wrp.12 for ; Thu, 08 Jul 2021 10:38:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=4V6pxp76MaEudx/IEK54W+rky4iXy/miG07jgmRH7DY=; b=BrRyknKgZV88ecMd94XiTUvwrdcF0uLLV6KBOjYoFXh1VuGj/8QahnhkFG4boL11gc GbkImyM9EaNR/hFZVGGQMl4i8i9ZpHHQE92NlVugO0ICg1P/HA3rEOAIq3bIO1y0+Gv+ 2TrCxbD4EOn129DwOalT6Q4Z6kfQ1/gn4e+8k= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=4V6pxp76MaEudx/IEK54W+rky4iXy/miG07jgmRH7DY=; b=jbffVzZfH4/wVwTOi4JX3LjbObP4+/pK4Rn30I12DXn2vSK4adZkbqTUFSIKNb2xpG USvc033ddIftmlrDEwU5FOVKYfaA7Sg2znm2vVNZYHRsNLdp1vE5CmE3+BDf1fvg08+t 9gLCbKH9+k4QkkExqvI4/g+lrgZxdskmHFZ/07H7VP//hSlf85p444uMcfBpQQAPM72n 2o4FZAUy0STpDz4Czyi4QhKxGH3lRHkd3gi+sDsSJSE6EQw2YSimI0Y3hEeajmUe4LY4 2Y215V8ITGq59cNThNnpIfwiOqAfx7p0RDogwZveg/QfSIT8ADJblwo2ZJV8Cm2HP1s5 85uA== X-Gm-Message-State: AOAM530PUmmQvfxPFt5mhSlZaiYV1jRuvyohrx/pbT/x3NVlVU8FXI4V PjFMR4qaKrmCc+08iSYChHTySSgkb7W2Jg== X-Google-Smtp-Source: ABdhPJxHYVh0KxReMYig08Pr0SYBUWnkEnvrgb57hPZUNr7/myKklgUeEQiVEXOTmXmKCBxKM8EriQ== X-Received: by 2002:a5d:634e:: with SMTP id b14mr35294595wrw.96.1625765889739; Thu, 08 Jul 2021 10:38:09 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id l4sm2521853wme.26.2021.07.08.10.38.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jul 2021 10:38:09 -0700 (PDT) From: Daniel Vetter To: DRI Development Subject: [PATCH v3 03/20] drm/sched: Barriers are needed for entity->last_scheduled Date: Thu, 8 Jul 2021 19:37:37 +0200 Message-Id: <20210708173754.3877540-4-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210708173754.3877540-1-daniel.vetter@ffwll.ch> References: <20210708173754.3877540-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , Intel Graphics Development , Steven Price , Boris Brezillon , Daniel Vetter , Lee Jones , =?UTF-8?q?Christian=20K=C3=B6nig?= Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" It might be good enough on x86 with just READ_ONCE, but the write side should then at least be WRITE_ONCE because x86 has total store order. It's definitely not enough on arm. Fix this proplery, which means - explain the need for the barrier in both places - point at the other side in each comment Also pull out the !sched_list case as the first check, so that the code flow is clearer. While at it sprinkle some comments around because it was very non-obvious to me what's actually going on here and why. Note that we really need full barriers here, at first I thought store-release and load-acquire on ->last_scheduled would be enough, but we actually requiring ordering between that and the queue state. Signed-off-by: Daniel Vetter Cc: "Christian König" Cc: Steven Price Cc: Daniel Vetter Cc: Andrey Grodzovsky Cc: Lee Jones Cc: Boris Brezillon --- drivers/gpu/drm/scheduler/sched_entity.c | 27 ++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 64d398166644..4e1124ed80e0 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -439,8 +439,16 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) dma_fence_set_error(&sched_job->s_fence->finished, -ECANCELED); dma_fence_put(entity->last_scheduled); + entity->last_scheduled = dma_fence_get(&sched_job->s_fence->finished); + /* + * if the queue is empty we allow drm_sched_job_arm() to locklessly + * access ->last_scheduled. This only works if we set the pointer before + * we dequeue and if we a write barrier here. + */ + smp_wmb(); + spsc_queue_pop(&entity->job_queue); return sched_job; } @@ -459,10 +467,25 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity) struct drm_gpu_scheduler *sched; struct drm_sched_rq *rq; - if (spsc_queue_count(&entity->job_queue) || !entity->sched_list) + /* single possible engine and already selected */ + if (!entity->sched_list) + return; + + /* queue non-empty, stay on the same engine */ + if (spsc_queue_count(&entity->job_queue)) return; - fence = READ_ONCE(entity->last_scheduled); + fence = entity->last_scheduled; + + /* + * Only when the queue is empty are we guaranteed the the scheduler + * thread cannot change ->last_scheduled. To enforce ordering we need + * a read barrier here. See drm_sched_entity_pop_job() for the other + * side. + */ + smp_rmb(); + + /* stay on the same engine if the previous job hasn't finished */ if (fence && !dma_fence_is_signaled(fence)) return; -- 2.32.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D71FC07E99 for ; Thu, 8 Jul 2021 17:38:22 +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 D2BD461879 for ; Thu, 8 Jul 2021 17:38:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2BD461879 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch 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 560B26E949; Thu, 8 Jul 2021 17:38:12 +0000 (UTC) Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by gabe.freedesktop.org (Postfix) with ESMTPS id 080E26E949 for ; Thu, 8 Jul 2021 17:38:11 +0000 (UTC) Received: by mail-wr1-x435.google.com with SMTP id p8so8565438wrr.1 for ; Thu, 08 Jul 2021 10:38:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=4V6pxp76MaEudx/IEK54W+rky4iXy/miG07jgmRH7DY=; b=BrRyknKgZV88ecMd94XiTUvwrdcF0uLLV6KBOjYoFXh1VuGj/8QahnhkFG4boL11gc GbkImyM9EaNR/hFZVGGQMl4i8i9ZpHHQE92NlVugO0ICg1P/HA3rEOAIq3bIO1y0+Gv+ 2TrCxbD4EOn129DwOalT6Q4Z6kfQ1/gn4e+8k= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=4V6pxp76MaEudx/IEK54W+rky4iXy/miG07jgmRH7DY=; b=HlT8qEuJ4uqcAxnr4hy1VOBs0RSMTauKowFvb6mZHd/5hlrgYqUM72cFWYrHKl+BMm RDSS4eSMEx5FoEGDsxY+2mD/oefAdj/apj4YPvRTrsZ55RmnsyYqjWwmVA3+T+cY1hww Eu/R8Ovp2IIqbiseVL7X5pqVxbJMeTeaJyF9UNi/EDAvDtC4ity7Fkxv8wiFg6rUDRhg lxUHQse4SU4tmrSOWyQo3RD/+joEIFfQWAAPRrFcn9tEXYH1Kdts4KXrxP/cFrV13Snn +6uIRGABTTNA7xf2LEAxmwyhDs3zBaSZB8xTAIURnuqwm2h4xwnDYrFn3ru1nULT1Xn+ 8QVA== X-Gm-Message-State: AOAM533dDFf+Y4k2GRzsnTWwpZIAGNbRUXjWXFvpMSRhEZIRgBqGrZmT ISIwtzXE0Ymk1tLIkBzZjiz7FA== X-Google-Smtp-Source: ABdhPJxHYVh0KxReMYig08Pr0SYBUWnkEnvrgb57hPZUNr7/myKklgUeEQiVEXOTmXmKCBxKM8EriQ== X-Received: by 2002:a5d:634e:: with SMTP id b14mr35294595wrw.96.1625765889739; Thu, 08 Jul 2021 10:38:09 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id l4sm2521853wme.26.2021.07.08.10.38.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jul 2021 10:38:09 -0700 (PDT) From: Daniel Vetter To: DRI Development Date: Thu, 8 Jul 2021 19:37:37 +0200 Message-Id: <20210708173754.3877540-4-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210708173754.3877540-1-daniel.vetter@ffwll.ch> References: <20210708173754.3877540-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v3 03/20] drm/sched: Barriers are needed for entity->last_scheduled X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrey Grodzovsky , Daniel Vetter , Intel Graphics Development , Steven Price , Daniel Vetter , Lee Jones , =?UTF-8?q?Christian=20K=C3=B6nig?= Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" SXQgbWlnaHQgYmUgZ29vZCBlbm91Z2ggb24geDg2IHdpdGgganVzdCBSRUFEX09OQ0UsIGJ1dCB0 aGUgd3JpdGUgc2lkZQpzaG91bGQgdGhlbiBhdCBsZWFzdCBiZSBXUklURV9PTkNFIGJlY2F1c2Ug eDg2IGhhcyB0b3RhbCBzdG9yZSBvcmRlci4KCkl0J3MgZGVmaW5pdGVseSBub3QgZW5vdWdoIG9u IGFybS4KCkZpeCB0aGlzIHByb3BsZXJ5LCB3aGljaCBtZWFucwotIGV4cGxhaW4gdGhlIG5lZWQg Zm9yIHRoZSBiYXJyaWVyIGluIGJvdGggcGxhY2VzCi0gcG9pbnQgYXQgdGhlIG90aGVyIHNpZGUg aW4gZWFjaCBjb21tZW50CgpBbHNvIHB1bGwgb3V0IHRoZSAhc2NoZWRfbGlzdCBjYXNlIGFzIHRo ZSBmaXJzdCBjaGVjaywgc28gdGhhdCB0aGUKY29kZSBmbG93IGlzIGNsZWFyZXIuCgpXaGlsZSBh dCBpdCBzcHJpbmtsZSBzb21lIGNvbW1lbnRzIGFyb3VuZCBiZWNhdXNlIGl0IHdhcyB2ZXJ5Cm5v bi1vYnZpb3VzIHRvIG1lIHdoYXQncyBhY3R1YWxseSBnb2luZyBvbiBoZXJlIGFuZCB3aHkuCgpO b3RlIHRoYXQgd2UgcmVhbGx5IG5lZWQgZnVsbCBiYXJyaWVycyBoZXJlLCBhdCBmaXJzdCBJIHRo b3VnaHQKc3RvcmUtcmVsZWFzZSBhbmQgbG9hZC1hY3F1aXJlIG9uIC0+bGFzdF9zY2hlZHVsZWQg d291bGQgYmUgZW5vdWdoLApidXQgd2UgYWN0dWFsbHkgcmVxdWlyaW5nIG9yZGVyaW5nIGJldHdl ZW4gdGhhdCBhbmQgdGhlIHF1ZXVlIHN0YXRlLgoKU2lnbmVkLW9mZi1ieTogRGFuaWVsIFZldHRl ciA8ZGFuaWVsLnZldHRlckBpbnRlbC5jb20+CkNjOiAiQ2hyaXN0aWFuIEvDtm5pZyIgPGNocmlz dGlhbi5rb2VuaWdAYW1kLmNvbT4KQ2M6IFN0ZXZlbiBQcmljZSA8c3RldmVuLnByaWNlQGFybS5j b20+CkNjOiBEYW5pZWwgVmV0dGVyIDxkYW5pZWwudmV0dGVyQGZmd2xsLmNoPgpDYzogQW5kcmV5 IEdyb2R6b3Zza3kgPGFuZHJleS5ncm9kem92c2t5QGFtZC5jb20+CkNjOiBMZWUgSm9uZXMgPGxl ZS5qb25lc0BsaW5hcm8ub3JnPgpDYzogQm9yaXMgQnJlemlsbG9uIDxib3Jpcy5icmV6aWxsb25A Y29sbGFib3JhLmNvbT4KLS0tCiBkcml2ZXJzL2dwdS9kcm0vc2NoZWR1bGVyL3NjaGVkX2VudGl0 eS5jIHwgMjcgKysrKysrKysrKysrKysrKysrKysrKy0tCiAxIGZpbGUgY2hhbmdlZCwgMjUgaW5z ZXJ0aW9ucygrKSwgMiBkZWxldGlvbnMoLSkKCmRpZmYgLS1naXQgYS9kcml2ZXJzL2dwdS9kcm0v c2NoZWR1bGVyL3NjaGVkX2VudGl0eS5jIGIvZHJpdmVycy9ncHUvZHJtL3NjaGVkdWxlci9zY2hl ZF9lbnRpdHkuYwppbmRleCA2NGQzOTgxNjY2NDQuLjRlMTEyNGVkODBlMCAxMDA2NDQKLS0tIGEv ZHJpdmVycy9ncHUvZHJtL3NjaGVkdWxlci9zY2hlZF9lbnRpdHkuYworKysgYi9kcml2ZXJzL2dw dS9kcm0vc2NoZWR1bGVyL3NjaGVkX2VudGl0eS5jCkBAIC00MzksOCArNDM5LDE2IEBAIHN0cnVj dCBkcm1fc2NoZWRfam9iICpkcm1fc2NoZWRfZW50aXR5X3BvcF9qb2Ioc3RydWN0IGRybV9zY2hl ZF9lbnRpdHkgKmVudGl0eSkKIAkJZG1hX2ZlbmNlX3NldF9lcnJvcigmc2NoZWRfam9iLT5zX2Zl bmNlLT5maW5pc2hlZCwgLUVDQU5DRUxFRCk7CiAKIAlkbWFfZmVuY2VfcHV0KGVudGl0eS0+bGFz dF9zY2hlZHVsZWQpOworCiAJZW50aXR5LT5sYXN0X3NjaGVkdWxlZCA9IGRtYV9mZW5jZV9nZXQo JnNjaGVkX2pvYi0+c19mZW5jZS0+ZmluaXNoZWQpOwogCisJLyoKKwkgKiBpZiB0aGUgcXVldWUg aXMgZW1wdHkgd2UgYWxsb3cgZHJtX3NjaGVkX2pvYl9hcm0oKSB0byBsb2NrbGVzc2x5CisJICog YWNjZXNzIC0+bGFzdF9zY2hlZHVsZWQuIFRoaXMgb25seSB3b3JrcyBpZiB3ZSBzZXQgdGhlIHBv aW50ZXIgYmVmb3JlCisJICogd2UgZGVxdWV1ZSBhbmQgaWYgd2UgYSB3cml0ZSBiYXJyaWVyIGhl cmUuCisJICovCisJc21wX3dtYigpOworCiAJc3BzY19xdWV1ZV9wb3AoJmVudGl0eS0+am9iX3F1 ZXVlKTsKIAlyZXR1cm4gc2NoZWRfam9iOwogfQpAQCAtNDU5LDEwICs0NjcsMjUgQEAgdm9pZCBk cm1fc2NoZWRfZW50aXR5X3NlbGVjdF9ycShzdHJ1Y3QgZHJtX3NjaGVkX2VudGl0eSAqZW50aXR5 KQogCXN0cnVjdCBkcm1fZ3B1X3NjaGVkdWxlciAqc2NoZWQ7CiAJc3RydWN0IGRybV9zY2hlZF9y cSAqcnE7CiAKLQlpZiAoc3BzY19xdWV1ZV9jb3VudCgmZW50aXR5LT5qb2JfcXVldWUpIHx8ICFl bnRpdHktPnNjaGVkX2xpc3QpCisJLyogc2luZ2xlIHBvc3NpYmxlIGVuZ2luZSBhbmQgYWxyZWFk eSBzZWxlY3RlZCAqLworCWlmICghZW50aXR5LT5zY2hlZF9saXN0KQorCQlyZXR1cm47CisKKwkv KiBxdWV1ZSBub24tZW1wdHksIHN0YXkgb24gdGhlIHNhbWUgZW5naW5lICovCisJaWYgKHNwc2Nf cXVldWVfY291bnQoJmVudGl0eS0+am9iX3F1ZXVlKSkKIAkJcmV0dXJuOwogCi0JZmVuY2UgPSBS RUFEX09OQ0UoZW50aXR5LT5sYXN0X3NjaGVkdWxlZCk7CisJZmVuY2UgPSBlbnRpdHktPmxhc3Rf c2NoZWR1bGVkOworCisJLyoKKwkgKiBPbmx5IHdoZW4gdGhlIHF1ZXVlIGlzIGVtcHR5IGFyZSB3 ZSBndWFyYW50ZWVkIHRoZSB0aGUgc2NoZWR1bGVyCisJICogdGhyZWFkIGNhbm5vdCBjaGFuZ2Ug LT5sYXN0X3NjaGVkdWxlZC4gVG8gZW5mb3JjZSBvcmRlcmluZyB3ZSBuZWVkCisJICogYSByZWFk IGJhcnJpZXIgaGVyZS4gU2VlIGRybV9zY2hlZF9lbnRpdHlfcG9wX2pvYigpIGZvciB0aGUgb3Ro ZXIKKwkgKiBzaWRlLgorCSAqLworCXNtcF9ybWIoKTsKKworCS8qIHN0YXkgb24gdGhlIHNhbWUg ZW5naW5lIGlmIHRoZSBwcmV2aW91cyBqb2IgaGFzbid0IGZpbmlzaGVkICovCiAJaWYgKGZlbmNl ICYmICFkbWFfZmVuY2VfaXNfc2lnbmFsZWQoZmVuY2UpKQogCQlyZXR1cm47CiAKLS0gCjIuMzIu MAoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KSW50ZWwt Z2Z4IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8v bGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vaW50ZWwtZ2Z4Cg==