From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934622AbcJUOzX (ORCPT ); Fri, 21 Oct 2016 10:55:23 -0400 Received: from mga06.intel.com ([134.134.136.31]:15345 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934306AbcJUOzU (ORCPT ); Fri, 21 Oct 2016 10:55:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,377,1473145200"; d="scan'208";a="1057179725" Subject: Re: [Intel-gfx] [PATCH 4/5] drm/i915: Use __sg_alloc_table_from_pages for allocating object backing store To: Chris Wilson , Tvrtko Ursulin , Intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, Tvrtko Ursulin References: <1477059083-3500-1-git-send-email-tvrtko.ursulin@linux.intel.com> <1477059083-3500-5-git-send-email-tvrtko.ursulin@linux.intel.com> <20161021142757.GP25629@nuc-i3427.alporthouse.com> From: Tvrtko Ursulin Message-ID: <79f299ba-ac59-4932-56e8-687a30ca43e2@linux.intel.com> Date: Fri, 21 Oct 2016 15:55:11 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161021142757.GP25629@nuc-i3427.alporthouse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/10/2016 15:27, Chris Wilson wrote: > On Fri, Oct 21, 2016 at 03:11:22PM +0100, Tvrtko Ursulin wrote: >> @@ -2236,18 +2233,16 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj) >> BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS); >> BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS); >> >> - max_segment = swiotlb_max_size(); >> - if (!max_segment) >> - max_segment = rounddown(UINT_MAX, PAGE_SIZE); >> - >> - st = kmalloc(sizeof(*st), GFP_KERNEL); >> - if (st == NULL) >> - return -ENOMEM; >> - >> page_count = obj->base.size / PAGE_SIZE; >> - if (sg_alloc_table(st, page_count, GFP_KERNEL)) { >> - kfree(st); >> + pages = drm_malloc_gfp(page_count, sizeof(struct page *), >> + GFP_TEMPORARY | __GFP_ZERO); >> + if (!pages) >> return -ENOMEM; > > Full circle! The whole reason this exists was to avoid that vmalloc. I > don't really want it back... Yes, it is not ideal. However all objects under 4 MiB should fall under the kmalloc fast path (8 KiB of struct page pointers, which should always be available), and possibly bigger ones as well if there is room. It only fallbacks to vmalloc for objects larger than 4 MiB, when it also fails to get the page pointer array from the SLAB (GFP_TEMPORARY). So perhaps SLAB would most of the time have some nice chunks for us to pretty much limit vmalloc apart for the huge objects? And then, is creation time for those so performance critical? I came up with this because I started to dislike my previous sg_trim_table approach as too ugly. It had an advantage of simplicity after fixing the theoretical chunk overflow in sg_alloc_table_from_pages. If we choose none of the two, only third option I can think of is to allocate the sg table as we add entries to it. I don't think it would be hard to do that. Regards, Tvrtko From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tvrtko Ursulin Subject: Re: [PATCH 4/5] drm/i915: Use __sg_alloc_table_from_pages for allocating object backing store Date: Fri, 21 Oct 2016 15:55:11 +0100 Message-ID: <79f299ba-ac59-4932-56e8-687a30ca43e2@linux.intel.com> References: <1477059083-3500-1-git-send-email-tvrtko.ursulin@linux.intel.com> <1477059083-3500-5-git-send-email-tvrtko.ursulin@linux.intel.com> <20161021142757.GP25629@nuc-i3427.alporthouse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1DBE36ED45 for ; Fri, 21 Oct 2016 14:55:14 +0000 (UTC) In-Reply-To: <20161021142757.GP25629@nuc-i3427.alporthouse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Chris Wilson , Tvrtko Ursulin , Intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, Tvrtko Ursulin List-Id: intel-gfx@lists.freedesktop.org Ck9uIDIxLzEwLzIwMTYgMTU6MjcsIENocmlzIFdpbHNvbiB3cm90ZToKPiBPbiBGcmksIE9jdCAy MSwgMjAxNiBhdCAwMzoxMToyMlBNICswMTAwLCBUdnJ0a28gVXJzdWxpbiB3cm90ZToKPj4gQEAg LTIyMzYsMTggKzIyMzMsMTYgQEAgaTkxNV9nZW1fb2JqZWN0X2dldF9wYWdlc19ndHQoc3RydWN0 IGRybV9pOTE1X2dlbV9vYmplY3QgKm9iaikKPj4gIAlCVUdfT04ob2JqLT5iYXNlLnJlYWRfZG9t YWlucyAmIEk5MTVfR0VNX0dQVV9ET01BSU5TKTsKPj4gIAlCVUdfT04ob2JqLT5iYXNlLndyaXRl X2RvbWFpbiAmIEk5MTVfR0VNX0dQVV9ET01BSU5TKTsKPj4KPj4gLQltYXhfc2VnbWVudCA9IHN3 aW90bGJfbWF4X3NpemUoKTsKPj4gLQlpZiAoIW1heF9zZWdtZW50KQo+PiAtCQltYXhfc2VnbWVu dCA9IHJvdW5kZG93bihVSU5UX01BWCwgUEFHRV9TSVpFKTsKPj4gLQo+PiAtCXN0ID0ga21hbGxv YyhzaXplb2YoKnN0KSwgR0ZQX0tFUk5FTCk7Cj4+IC0JaWYgKHN0ID09IE5VTEwpCj4+IC0JCXJl dHVybiAtRU5PTUVNOwo+PiAtCj4+ICAJcGFnZV9jb3VudCA9IG9iai0+YmFzZS5zaXplIC8gUEFH RV9TSVpFOwo+PiAtCWlmIChzZ19hbGxvY190YWJsZShzdCwgcGFnZV9jb3VudCwgR0ZQX0tFUk5F TCkpIHsKPj4gLQkJa2ZyZWUoc3QpOwo+PiArCXBhZ2VzID0gZHJtX21hbGxvY19nZnAocGFnZV9j b3VudCwgc2l6ZW9mKHN0cnVjdCBwYWdlICopLAo+PiArCQkJICAgICAgIEdGUF9URU1QT1JBUlkg fCBfX0dGUF9aRVJPKTsKPj4gKwlpZiAoIXBhZ2VzKQo+PiAgCQlyZXR1cm4gLUVOT01FTTsKPgo+ IEZ1bGwgY2lyY2xlISBUaGUgd2hvbGUgcmVhc29uIHRoaXMgZXhpc3RzIHdhcyB0byBhdm9pZCB0 aGF0IHZtYWxsb2MuIEkKPiBkb24ndCByZWFsbHkgd2FudCBpdCBiYWNrLi4uCgpZZXMsIGl0IGlz IG5vdCBpZGVhbC4KCkhvd2V2ZXIgYWxsIG9iamVjdHMgdW5kZXIgNCBNaUIgc2hvdWxkIGZhbGwg dW5kZXIgdGhlIGttYWxsb2MgZmFzdCBwYXRoIAooOCBLaUIgb2Ygc3RydWN0IHBhZ2UgcG9pbnRl cnMsIHdoaWNoIHNob3VsZCBhbHdheXMgYmUgYXZhaWxhYmxlKSwgYW5kIApwb3NzaWJseSBiaWdn ZXIgb25lcyBhcyB3ZWxsIGlmIHRoZXJlIGlzIHJvb20uCgpJdCBvbmx5IGZhbGxiYWNrcyB0byB2 bWFsbG9jIGZvciBvYmplY3RzIGxhcmdlciB0aGFuIDQgTWlCLCB3aGVuIGl0IGFsc28gCmZhaWxz IHRvIGdldCB0aGUgcGFnZSBwb2ludGVyIGFycmF5IGZyb20gdGhlIFNMQUIgKEdGUF9URU1QT1JB UlkpLgoKU28gcGVyaGFwcyBTTEFCIHdvdWxkIG1vc3Qgb2YgdGhlIHRpbWUgaGF2ZSBzb21lIG5p Y2UgY2h1bmtzIGZvciB1cyB0byAKcHJldHR5IG11Y2ggbGltaXQgdm1hbGxvYyBhcGFydCBmb3Ig dGhlIGh1Z2Ugb2JqZWN0cz8gQW5kIHRoZW4sIGlzIApjcmVhdGlvbiB0aW1lIGZvciB0aG9zZSBz byBwZXJmb3JtYW5jZSBjcml0aWNhbD8KCkkgY2FtZSB1cCB3aXRoIHRoaXMgYmVjYXVzZSBJIHN0 YXJ0ZWQgdG8gZGlzbGlrZSBteSBwcmV2aW91cyAKc2dfdHJpbV90YWJsZSBhcHByb2FjaCBhcyB0 b28gdWdseS4gSXQgaGFkIGFuIGFkdmFudGFnZSBvZiBzaW1wbGljaXR5IAphZnRlciBmaXhpbmcg dGhlIHRoZW9yZXRpY2FsIGNodW5rIG92ZXJmbG93IGluIHNnX2FsbG9jX3RhYmxlX2Zyb21fcGFn ZXMuCgpJZiB3ZSBjaG9vc2Ugbm9uZSBvZiB0aGUgdHdvLCBvbmx5IHRoaXJkIG9wdGlvbiBJIGNh biB0aGluayBvZiBpcyB0byAKYWxsb2NhdGUgdGhlIHNnIHRhYmxlIGFzIHdlIGFkZCBlbnRyaWVz IHRvIGl0LiBJIGRvbid0IHRoaW5rIGl0IHdvdWxkIGJlIApoYXJkIHRvIGRvIHRoYXQuCgpSZWdh cmRzLAoKVHZydGtvCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fCkludGVsLWdmeCBtYWlsaW5nIGxpc3QKSW50ZWwtZ2Z4QGxpc3RzLmZyZWVkZXNrdG9wLm9y ZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2ludGVsLWdm eAo=