From patchwork Wed May 7 05:21:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Widawsky X-Patchwork-Id: 4125571 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A14BCBFF02 for ; Wed, 7 May 2014 05:21:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D443920165 for ; Wed, 7 May 2014 05:21:44 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id D5641201BA for ; Wed, 7 May 2014 05:21:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7F8546EC24; Tue, 6 May 2014 22:21:42 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga03.intel.com (mga03.intel.com [143.182.124.21]) by gabe.freedesktop.org (Postfix) with ESMTP id D890C6EC25 for ; Tue, 6 May 2014 22:21:41 -0700 (PDT) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by azsmga101.ch.intel.com with ESMTP; 06 May 2014 22:21:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos; i="4.97,1001,1389772800"; d="scan'208"; a="527541097" Received: from unknown (HELO ironside.intel.com) ([10.255.12.78]) by fmsmga001.fm.intel.com with ESMTP; 06 May 2014 22:21:40 -0700 From: Ben Widawsky To: Intel GFX Date: Tue, 6 May 2014 22:21:33 -0700 Message-Id: <1399440098-17378-4-git-send-email-benjamin.widawsky@intel.com> X-Mailer: git-send-email 1.9.2 In-Reply-To: <1399440098-17378-1-git-send-email-benjamin.widawsky@intel.com> References: <1399440098-17378-1-git-send-email-benjamin.widawsky@intel.com> Cc: Ben Widawsky , Ben Widawsky Subject: [Intel-gfx] [PATCH 4/9] drm/i915: Limit the number of node allocation retries X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP AFAICT, it's impossible to actually infinitely retry the allocation in our current code. However, a small oversight on my part, slight bug, or future bug, could easily change that. To avoid a potential breakage, a simple retry variable of 16 bits will help us prevent infinitely running. Retry is limited to 100 as a mostly random number. Some consideration about stack usage was taken into account. As an example, if we allowed 256 retries on a 32b arch (and my memory serves that all arguments are passed on the stack for such architectures), thats 33 bytes * 256 retries + (fudge for return address and such)... it's way more than we want to use already. 64b architectures might be slightly better, since 6? of the first args will get passed through registers, but it's still bad. If anything, we might want to do way less than 100, like 3. Signed-off-by: Ben Widawsky --- drivers/gpu/drm/i915/i915_gem.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index b6965a2..de98b26 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3216,6 +3216,7 @@ static void i915_gem_verify_gtt(struct drm_device *dev) #endif } +#define MAX_VMA_FIND_RETRY 100 static int i915_gem_find_vm_space(struct i915_address_space *vm, struct drm_mm_node *node, @@ -3224,7 +3225,8 @@ i915_gem_find_vm_space(struct i915_address_space *vm, unsigned long color, unsigned long start, unsigned long end, - uint32_t flags) + uint32_t flags, + uint8_t retry) { int ret; ret = drm_mm_insert_node_in_range_generic(&vm->mm, node, @@ -3232,7 +3234,7 @@ i915_gem_find_vm_space(struct i915_address_space *vm, start, end, DRM_MM_SEARCH_DEFAULT, DRM_MM_CREATE_DEFAULT); - if (ret) { + if (ret && (retry < MAX_VMA_FIND_RETRY)) { if (WARN_ON(ret != -ENOSPC)) return ret; @@ -3241,7 +3243,8 @@ i915_gem_find_vm_space(struct i915_address_space *vm, if (ret == 0) return i915_gem_find_vm_space(vm, node, size, align, color, - start, end, flags); + start, end, flags, + retry++); } return ret; @@ -3306,8 +3309,9 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj, if (IS_ERR(vma)) goto err_unpin; - ret = i915_gem_find_vm_space(vm, &vma->node, size, alignment, - obj->cache_level, 0, gtt_max, flags); + ret = i915_gem_find_vm_space(vm, &vma->node, + size, alignment, obj->cache_level, + 0, gtt_max, flags, 1); if (ret) goto err_free_vma;