From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f50.google.com (mail-wm0-f50.google.com [74.125.82.50]) by kanga.kvack.org (Postfix) with ESMTP id D395B6B0254 for ; Wed, 25 Nov 2015 14:06:21 -0500 (EST) Received: by wmww144 with SMTP id w144so192612493wmw.1 for ; Wed, 25 Nov 2015 11:06:21 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id t82si7684152wmg.38.2015.11.25.11.06.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Nov 2015 11:06:20 -0800 (PST) Date: Wed, 25 Nov 2015 14:06:10 -0500 From: Johannes Weiner Subject: Re: [PATCH v2] drm/i915: Disable shrinker for non-swapped backed objects Message-ID: <20151125190610.GA12238@cmpxchg.org> References: <20151124231738.GA15770@nuc-i3427.alporthouse.com> <1448476616-5257-1-git-send-email-chris@chris-wilson.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448476616-5257-1-git-send-email-chris@chris-wilson.co.uk> Sender: owner-linux-mm@kvack.org List-ID: To: Chris Wilson Cc: intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, Akash Goel , sourab.gupta@intel.com On Wed, Nov 25, 2015 at 06:36:56PM +0000, Chris Wilson wrote: > If the system has no available swap pages, we cannot make forward > progress in the shrinker by releasing active pages, only by releasing > purgeable pages which are immediately reaped. Take total_swap_pages into > account when counting up available objects to be shrunk and subsequently > shrinking them. By doing so, we avoid unbinding objects that cannot be > shrunk and so wasting CPU cycles flushing those objects from the GPU to > the system and then immediately back again (as they will more than > likely be reused shortly after). > > Based on a patch by Akash Goel. > > v2: Check for frontswap without physical swap (or dedicated swap space). > If frontswap is available, we may be able to compress the GPU pages > instead of swapping out to disk. In this case, we do want to shrink GPU > objects and so make them available for compressing. Frontswap always sits on top of an active swap device. It's enough to check for available swap space. > +static bool swap_available(void) > +{ > + return total_swap_pages || frontswap_enabled; > +} If you use get_nr_swap_pages() instead of total_swap_pages, this will also stop scanning objects once the swap space is full. We do that in the VM to stop scanning anonymous pages. On a sidenote, frontswap_enabled is #defined to 1 when the feature is compiled in, so this would be a no-op on most distro kernels. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org