Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757745Ab0LTNzm (ORCPT ); Mon, 20 Dec 2010 08:55:42 -0500 Received: from router-fw.net-space.pl ([89.174.63.77]:51368 "EHLO router-fw.net-space.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757727Ab0LTNzk (ORCPT ); Mon, 20 Dec 2010 08:55:40 -0500 X-Greylist: delayed 439 seconds by postgrey-1.27 at vger.kernel.org; Mon, 20 Dec 2010 08:55:39 EST Date: Mon, 20 Dec 2010 14:47:24 +0100 From: Daniel Kiper To: akpm@linux-foundation.org, andi.kleen@intel.com, haicheng.li@linux.intel.com, fengguang.wu@intel.com, jeremy@goop.org, konrad.wilk@oracle.com, dan.magenheimer@oracle.com, v.tolstov@selfip.ru, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 2/3] drivers/xen/balloon.c: Various balloon features and fixes Message-ID: <20101220134724.GC6749@router-fw-old.local.net-space.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10255 Lines: 341 Features and fixes: - HVM mode is supported now, - migration from mod_timer() to schedule_delayed_work(), - removal of driver_pages (I do not have seen any references to it), - protect before CPU exhaust by event/x process during errors by adding some delays in scheduling next event, - some other minor fixes. Signed-off-by: Daniel Kiper --- arch/x86/xen/mmu.c | 3 +- drivers/xen/balloon.c | 128 +++++++++++++++++++++++++++++++++---------------- 2 files changed, 87 insertions(+), 44 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 42086ac..6278650 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -75,8 +75,7 @@ /* * Protects atomic reservation decrease/increase against concurrent increases. - * Also protects non-atomic updates of current_pages and driver_pages, and - * balloon lists. + * Also protects non-atomic updates of current_pages and balloon lists. */ DEFINE_SPINLOCK(xen_reservation_lock); diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 500290b..06dbdad 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -69,14 +69,11 @@ struct balloon_stats { /* We aim for 'current allocation' == 'target allocation'. */ unsigned long current_pages; unsigned long target_pages; - /* - * Drivers may alter the memory reservation independently, but they - * must inform the balloon driver so we avoid hitting the hard limit. - */ - unsigned long driver_pages; /* Number of pages in high- and low-memory balloons. */ unsigned long balloon_low; unsigned long balloon_high; + unsigned long schedule_delay; + unsigned long max_schedule_delay; }; static DEFINE_MUTEX(balloon_mutex); @@ -103,15 +100,14 @@ static LIST_HEAD(ballooned_pages); /* Main work function, always executed in process context. */ static void balloon_process(struct work_struct *work); -static DECLARE_WORK(balloon_worker, balloon_process); -static struct timer_list balloon_timer; +static DECLARE_DELAYED_WORK(balloon_worker, balloon_process); /* When ballooning out (allocating memory to return to Xen) we don't really want the kernel to try too hard since that can trigger the oom killer. */ #define GFP_BALLOON \ (GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC) -static void scrub_page(struct page *page) +static inline void scrub_page(struct page *page) { #ifdef CONFIG_XEN_SCRUB_PAGES clear_highpage(page); @@ -172,9 +168,29 @@ static struct page *balloon_next_page(struct page *page) return list_entry(next, struct page, lru); } -static void balloon_alarm(unsigned long unused) +static void update_schedule_delay(int cmd) { - schedule_work(&balloon_worker); + unsigned long new_schedule_delay; + + /* + * cmd >= 0: balloon_stats.schedule_delay = 1, + * cmd < 0: increase balloon_stats.schedule_delay but + * no more than balloon_stats.max_schedule_delay. + */ + + if (cmd >= 0) { + balloon_stats.schedule_delay = 1; + return; + } + + new_schedule_delay = balloon_stats.schedule_delay << 1; + + if (new_schedule_delay > balloon_stats.max_schedule_delay) { + balloon_stats.schedule_delay = balloon_stats.max_schedule_delay; + return; + } + + balloon_stats.schedule_delay = new_schedule_delay; } static unsigned long current_target(void) @@ -191,9 +207,9 @@ static unsigned long current_target(void) static int increase_reservation(unsigned long nr_pages) { + int rc, state = 0; unsigned long pfn, i, flags; struct page *page; - long rc; struct xen_memory_reservation reservation = { .address_bits = 0, .extent_order = 0, @@ -206,8 +222,17 @@ static int increase_reservation(unsigned long nr_pages) spin_lock_irqsave(&xen_reservation_lock, flags); page = balloon_first_page(); + + if (!page) { + state = -ENOMEM; + goto out; + } + for (i = 0; i < nr_pages; i++) { - BUG_ON(page == NULL); + if (!page) { + nr_pages = i; + break; + } frame_list[i] = page_to_pfn(page); page = balloon_next_page(page); } @@ -215,8 +240,11 @@ static int increase_reservation(unsigned long nr_pages) set_xen_guest_handle(reservation.extent_start, frame_list); reservation.nr_extents = nr_pages; rc = HYPERVISOR_memory_op(XENMEM_populate_physmap, &reservation); - if (rc < 0) - goto out; + if (rc < nr_pages) { + state = (rc <= 0) ? -ENOMEM : 1; + if (rc <= 0) + goto out; + } for (i = 0; i < rc; i++) { page = balloon_retrieve(); @@ -229,7 +257,7 @@ static int increase_reservation(unsigned long nr_pages) set_phys_to_machine(pfn, frame_list[i]); /* Link back into the page tables if not highmem. */ - if (pfn < max_low_pfn) { + if (xen_pv_domain() && !PageHighMem(page)) { int ret; ret = HYPERVISOR_update_va_mapping( (unsigned long)__va(pfn << PAGE_SHIFT), @@ -249,15 +277,14 @@ static int increase_reservation(unsigned long nr_pages) out: spin_unlock_irqrestore(&xen_reservation_lock, flags); - return rc < 0 ? rc : rc != nr_pages; + return state; } static int decrease_reservation(unsigned long nr_pages) { unsigned long pfn, i, flags; struct page *page; - int need_sleep = 0; - int ret; + int ret, state = 0; struct xen_memory_reservation reservation = { .address_bits = 0, .extent_order = 0, @@ -270,7 +297,7 @@ static int decrease_reservation(unsigned long nr_pages) for (i = 0; i < nr_pages; i++) { if ((page = alloc_page(GFP_BALLOON)) == NULL) { nr_pages = i; - need_sleep = 1; + state = -ENOMEM; break; } @@ -279,7 +306,7 @@ static int decrease_reservation(unsigned long nr_pages) scrub_page(page); - if (!PageHighMem(page)) { + if (xen_pv_domain() && !PageHighMem(page)) { ret = HYPERVISOR_update_va_mapping( (unsigned long)__va(pfn << PAGE_SHIFT), __pte_ma(0), 0); @@ -310,7 +337,7 @@ static int decrease_reservation(unsigned long nr_pages) spin_unlock_irqrestore(&xen_reservation_lock, flags); - return need_sleep; + return state; } /* @@ -321,27 +348,41 @@ static int decrease_reservation(unsigned long nr_pages) */ static void balloon_process(struct work_struct *work) { - int need_sleep = 0; + int rc, state = 0; long credit; mutex_lock(&balloon_mutex); do { credit = current_target() - balloon_stats.current_pages; - if (credit > 0) - need_sleep = (increase_reservation(credit) != 0); - if (credit < 0) - need_sleep = (decrease_reservation(-credit) != 0); + + /* + * state > 0: hungry, + * state == 0: done or nothing to do, + * state < 0: error, go to sleep. + */ + + if (credit > 0) { + rc = increase_reservation(credit); + state = (rc < 0) ? rc : state; + } + + if (credit < 0) { + rc = decrease_reservation(-credit); + state = (rc < 0) ? rc : state; + } + + update_schedule_delay(state); #ifndef CONFIG_PREEMPT if (need_resched()) schedule(); #endif - } while ((credit != 0) && !need_sleep); + } while (credit && state >= 0); /* Schedule more work if there is some still to be done. */ - if (current_target() != balloon_stats.current_pages) - mod_timer(&balloon_timer, jiffies + HZ); + if (state < 0) + schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ); mutex_unlock(&balloon_mutex); } @@ -351,7 +392,7 @@ static void balloon_set_new_target(unsigned long target) { /* No need for lock. Not read-modify-write updates. */ balloon_stats.target_pages = target; - schedule_work(&balloon_worker); + schedule_delayed_work(&balloon_worker, 0); } static struct xenbus_watch target_watch = @@ -395,28 +436,28 @@ static struct notifier_block xenstore_notifier; static int __init balloon_init(void) { - unsigned long pfn; + unsigned long pfn, nr_pages; struct page *page; - if (!xen_pv_domain()) + if (!xen_domain()) return -ENODEV; pr_info("xen_balloon: Initialising balloon driver.\n"); - balloon_stats.current_pages = min(xen_start_info->nr_pages, max_pfn); + nr_pages = xen_pv_domain() ? xen_start_info->nr_pages : max_pfn; + + balloon_stats.current_pages = min(nr_pages, max_pfn); balloon_stats.target_pages = balloon_stats.current_pages; balloon_stats.balloon_low = 0; balloon_stats.balloon_high = 0; - balloon_stats.driver_pages = 0UL; - init_timer(&balloon_timer); - balloon_timer.data = 0; - balloon_timer.function = balloon_alarm; + balloon_stats.schedule_delay = 1; + balloon_stats.max_schedule_delay = 32; register_balloon(&balloon_sysdev); /* Initialise the balloon with excess memory space. */ - for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) { + for (pfn = nr_pages; pfn < max_pfn; pfn++) { page = pfn_to_page(pfn); if (!PageReserved(page)) balloon_append(page); @@ -452,7 +493,9 @@ module_exit(balloon_exit); BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); -BALLOON_SHOW(driver_kb, "%lu\n", PAGES2KB(balloon_stats.driver_pages)); + +static SYSDEV_ULONG_ATTR(schedule_delay, 0644, balloon_stats.schedule_delay); +static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, char *buf) @@ -515,23 +558,24 @@ static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, static struct sysdev_attribute *balloon_attrs[] = { &attr_target_kb, &attr_target, + &attr_schedule_delay.attr, + &attr_max_schedule_delay.attr }; static struct attribute *balloon_info_attrs[] = { &attr_current_kb.attr, &attr_low_kb.attr, &attr_high_kb.attr, - &attr_driver_kb.attr, NULL }; static struct attribute_group balloon_info_group = { .name = "info", - .attrs = balloon_info_attrs, + .attrs = balloon_info_attrs }; static struct sysdev_class balloon_sysdev_class = { - .name = BALLOON_CLASS_NAME, + .name = BALLOON_CLASS_NAME }; static int register_balloon(struct sys_device *sysdev) -- 1.4.4.4 -- 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/