From patchwork Sat May 3 17:56:01 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Widawsky X-Patchwork-Id: 4106301 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 2454EBFF02 for ; Sat, 3 May 2014 17:56:52 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4876120155 for ; Sat, 3 May 2014 17:56:51 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 662E42014A for ; Sat, 3 May 2014 17:56:50 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E22386E6B9; Sat, 3 May 2014 10:56:49 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mail.bwidawsk.net (bwidawsk.net [166.78.191.112]) by gabe.freedesktop.org (Postfix) with ESMTP id 759ED6E6B5 for ; Sat, 3 May 2014 10:56:48 -0700 (PDT) Received: by mail.bwidawsk.net (Postfix, from userid 5001) id F18985801B; Sat, 3 May 2014 10:56:45 -0700 (PDT) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: 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 Received: from ironside.kumite (c-24-21-100-90.hsd1.or.comcast.net [24.21.100.90]) by mail.bwidawsk.net (Postfix) with ESMTPSA id 509C158012; Sat, 3 May 2014 10:56:11 -0700 (PDT) From: Ben Widawsky To: Intel GFX Date: Sat, 3 May 2014 10:56:01 -0700 Message-Id: <1399139762-20728-5-git-send-email-benjamin.widawsky@intel.com> X-Mailer: git-send-email 1.9.2 In-Reply-To: <1399139762-20728-1-git-send-email-benjamin.widawsky@intel.com> References: <1399139762-20728-1-git-send-email-benjamin.widawsky@intel.com> Cc: Ben Widawsky , Ben Widawsky Subject: [Intel-gfx] [PATCH 4/5] 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-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 1f85ec5..c60365a 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;