Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750934AbbGXSzw (ORCPT ); Fri, 24 Jul 2015 14:55:52 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:38742 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752928AbbGXSzv (ORCPT ); Fri, 24 Jul 2015 14:55:51 -0400 Date: Fri, 24 Jul 2015 14:55:45 -0400 From: Konrad Rzeszutek Wilk To: David Vrabel Cc: xen-devel@lists.xenproject.org, Boris Ostrovsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Daniel Kiper Subject: Re: [PATCHv2 08/10] xen/balloon: use hotplugged pages for foreign mappings etc. Message-ID: <20150724185545.GD12824@l.oracle.com> References: <1437738468-24110-1-git-send-email-david.vrabel@citrix.com> <1437738468-24110-9-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437738468-24110-9-git-send-email-david.vrabel@citrix.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4613 Lines: 135 On Fri, Jul 24, 2015 at 12:47:46PM +0100, David Vrabel wrote: > alloc_xenballooned_pages() is used to get ballooned pages to back > foreign mappings etc. Instead of having to balloon out real pages, > use (if supported) hotplugged memory. > > This makes more memory available to the guest and reduces > fragmentation in the p2m. > > If userspace is lacking a udev rule (or similar) to online hotplugged Is that udev rule already in distros? > regions automatically, alloc_xenballooned_pages() will timeout and > fall back to the old behaviour of ballooning out pages. > > Signed-off-by: David Vrabel > Reviewed-by: Daniel Kiper > --- > drivers/xen/balloon.c | 32 ++++++++++++++++++++++++++------ > include/xen/balloon.h | 1 + > 2 files changed, 27 insertions(+), 6 deletions(-) > > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index cc68a4d..fd6970f3 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -99,6 +99,7 @@ static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)]; > > /* List of ballooned pages, threaded through the mem_map array. */ > static LIST_HEAD(ballooned_pages); > +static DECLARE_WAIT_QUEUE_HEAD(balloon_wq); > > /* Main work function, always executed in process context. */ > static void balloon_process(struct work_struct *work); > @@ -127,6 +128,7 @@ static void __balloon_append(struct page *page) > list_add(&page->lru, &ballooned_pages); > balloon_stats.balloon_low++; > } > + wake_up(&balloon_wq); > } > > static void balloon_append(struct page *page) > @@ -253,7 +255,8 @@ static enum bp_state reserve_additional_memory(void) > int nid, rc; > unsigned long balloon_hotplug; > > - credit = balloon_stats.target_pages - balloon_stats.total_pages; > + credit = balloon_stats.target_pages + balloon_stats.target_unpopulated > + - balloon_stats.total_pages; > > /* > * Already hotplugged enough pages? Wait for them to be > @@ -334,7 +337,7 @@ static struct notifier_block xen_memory_nb = { > static enum bp_state reserve_additional_memory(void) > { > balloon_stats.target_pages = balloon_stats.current_pages; > - return BP_DONE; > + return BP_ECANCELED; > } > #endif /* CONFIG_XEN_BALLOON_MEMORY_HOTPLUG */ > > @@ -538,13 +541,31 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages) > { > int pgno = 0; > struct page *page; > + > mutex_lock(&balloon_mutex); > + > + balloon_stats.target_unpopulated += nr_pages; > + > while (pgno < nr_pages) { > page = balloon_retrieve(true); > if (page) { > pages[pgno++] = page; > } else { > enum bp_state st; > + > + st = reserve_additional_memory(); > + if (st != BP_ECANCELED) { > + int ret; > + > + mutex_unlock(&balloon_mutex); > + ret = wait_event_timeout(balloon_wq, > + !list_empty(&ballooned_pages), > + msecs_to_jiffies(100)); > + mutex_lock(&balloon_mutex); > + if (ret > 0) > + continue; > + } > + > st = decrease_reservation(nr_pages - pgno, GFP_USER); > if (st != BP_DONE) > goto out_undo; > @@ -553,11 +574,8 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages) > mutex_unlock(&balloon_mutex); > return 0; > out_undo: > - while (pgno) > - balloon_append(pages[--pgno]); > - /* Free the memory back to the kernel soon */ > - schedule_delayed_work(&balloon_worker, 0); > mutex_unlock(&balloon_mutex); > + free_xenballooned_pages(pgno, pages); > return -ENOMEM; > } > EXPORT_SYMBOL(alloc_xenballooned_pages); > @@ -578,6 +596,8 @@ void free_xenballooned_pages(int nr_pages, struct page **pages) > balloon_append(pages[i]); > } > > + balloon_stats.target_unpopulated -= nr_pages; > + > /* The balloon may be too large now. Shrink it if needed. */ > if (current_credit()) > schedule_delayed_work(&balloon_worker, 0); > diff --git a/include/xen/balloon.h b/include/xen/balloon.h > index 83efdeb..d1767df 100644 > --- a/include/xen/balloon.h > +++ b/include/xen/balloon.h > @@ -8,6 +8,7 @@ struct balloon_stats { > /* We aim for 'current allocation' == 'target allocation'. */ > unsigned long current_pages; > unsigned long target_pages; > + unsigned long target_unpopulated; > /* Number of pages in high- and low-memory balloons. */ > unsigned long balloon_low; > unsigned long balloon_high; > -- > 2.1.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/