From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933694AbZDHMHw (ORCPT ); Wed, 8 Apr 2009 08:07:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764621AbZDHMAk (ORCPT ); Wed, 8 Apr 2009 08:00:40 -0400 Received: from brick.kernel.dk ([93.163.65.50]:48914 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933385AbZDHMAV (ORCPT ); Wed, 8 Apr 2009 08:00:21 -0400 From: Jens Axboe To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: chris.mason@oracle.com, david@fromorbit.com, hch@infradead.org, akpm@linux-foundation.org, jack@suse.cz, Jens Axboe Subject: [PATCH 04/13] writeback get rid of pdflush completely Date: Wed, 8 Apr 2009 14:00:07 +0200 Message-Id: <1239192016-19857-5-git-send-email-jens.axboe@oracle.com> X-Mailer: git-send-email 1.6.2.2.446.gfbdc0 In-Reply-To: <1239192016-19857-1-git-send-email-jens.axboe@oracle.com> References: <1239192016-19857-1-git-send-email-jens.axboe@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is now unused, so kill it off. Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 5 + include/linux/writeback.h | 12 -- mm/Makefile | 2 +- mm/pdflush.c | 276 --------------------------------------------- 4 files changed, 6 insertions(+), 289 deletions(-) delete mode 100644 mm/pdflush.c diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index bc188cb..816cf8e 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -29,6 +29,11 @@ #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) +/* + * We don't actually have pdflush, but this one is exported though /proc... + */ +int nr_pdflush_threads = 0; + /** * writeback_acquire - attempt to get exclusive writeback access to a device * @bdi: the device's backing_dev_info structure diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 0bc5af3..f241794 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -14,17 +14,6 @@ extern struct list_head inode_in_use; extern struct list_head inode_unused; /* - * Yes, writeback.h requires sched.h - * No, sched.h is not included from here. - */ -static inline int task_is_pdflush(struct task_struct *task) -{ - return task->flags & PF_FLUSHER; -} - -#define current_is_pdflush() task_is_pdflush(current) - -/* * fs/fs-writeback.c */ enum writeback_sync_modes { @@ -151,7 +140,6 @@ balance_dirty_pages_ratelimited(struct address_space *mapping) typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, void *data); -int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); int generic_writepages(struct address_space *mapping, struct writeback_control *wbc); int write_cache_pages(struct address_space *mapping, diff --git a/mm/Makefile b/mm/Makefile index ec73c68..2adb811 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \ vmalloc.o obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \ - maccess.o page_alloc.o page-writeback.o pdflush.o \ + maccess.o page_alloc.o page-writeback.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \ page_isolation.o mm_init.o $(mmu-y) diff --git a/mm/pdflush.c b/mm/pdflush.c deleted file mode 100644 index f2caf96..0000000 --- a/mm/pdflush.c +++ /dev/null @@ -1,276 +0,0 @@ -/* - * mm/pdflush.c - worker threads for writing back filesystem data - * - * Copyright (C) 2002, Linus Torvalds. - * - * 09Apr2002 Andrew Morton - * Initial version - * 29Feb2004 kaos@sgi.com - * Move worker thread creation to kthread to avoid chewing - * up stack space with nested calls to kernel_thread. - */ - -#include -#include -#include -#include -#include -#include -#include -#include /* Needed by writeback.h */ -#include /* Prototypes pdflush_operation() */ -#include -#include -#include - - -/* - * Minimum and maximum number of pdflush instances - */ -#define MIN_PDFLUSH_THREADS 2 -#define MAX_PDFLUSH_THREADS 8 - -static void start_one_pdflush_thread(void); - - -/* - * The pdflush threads are worker threads for writing back dirty data. - * Ideally, we'd like one thread per active disk spindle. But the disk - * topology is very hard to divine at this level. Instead, we take - * care in various places to prevent more than one pdflush thread from - * performing writeback against a single filesystem. pdflush threads - * have the PF_FLUSHER flag set in current->flags to aid in this. - */ - -/* - * All the pdflush threads. Protected by pdflush_lock - */ -static LIST_HEAD(pdflush_list); -static DEFINE_SPINLOCK(pdflush_lock); - -/* - * The count of currently-running pdflush threads. Protected - * by pdflush_lock. - * - * Readable by sysctl, but not writable. Published to userspace at - * /proc/sys/vm/nr_pdflush_threads. - */ -int nr_pdflush_threads = 0; - -/* - * The max/min number of pdflush threads. R/W by sysctl at - * /proc/sys/vm/nr_pdflush_threads_max/min - */ -int nr_pdflush_threads_max __read_mostly = MAX_PDFLUSH_THREADS; -int nr_pdflush_threads_min __read_mostly = MIN_PDFLUSH_THREADS; - - -/* - * The time at which the pdflush thread pool last went empty - */ -static unsigned long last_empty_jifs; - -/* - * The pdflush thread. - * - * Thread pool management algorithm: - * - * - The minimum and maximum number of pdflush instances are bound - * by nr_pdflush_threads_min and nr_pdflush_threads_max. - * - * - If there have been no idle pdflush instances for 1 second, create - * a new one. - * - * - If the least-recently-went-to-sleep pdflush thread has been asleep - * for more than one second, terminate a thread. - */ - -/* - * A structure for passing work to a pdflush thread. Also for passing - * state information between pdflush threads. Protected by pdflush_lock. - */ -struct pdflush_work { - struct task_struct *who; /* The thread */ - void (*fn)(unsigned long); /* A callback function */ - unsigned long arg0; /* An argument to the callback */ - struct list_head list; /* On pdflush_list, when idle */ - unsigned long when_i_went_to_sleep; -}; - -static int __pdflush(struct pdflush_work *my_work) -{ - current->flags |= PF_FLUSHER | PF_SWAPWRITE; - set_freezable(); - my_work->fn = NULL; - my_work->who = current; - INIT_LIST_HEAD(&my_work->list); - - spin_lock_irq(&pdflush_lock); - for ( ; ; ) { - struct pdflush_work *pdf; - - set_current_state(TASK_INTERRUPTIBLE); - list_move(&my_work->list, &pdflush_list); - my_work->when_i_went_to_sleep = jiffies; - spin_unlock_irq(&pdflush_lock); - schedule(); - try_to_freeze(); - spin_lock_irq(&pdflush_lock); - if (!list_empty(&my_work->list)) { - /* - * Someone woke us up, but without removing our control - * structure from the global list. swsusp will do this - * in try_to_freeze()->refrigerator(). Handle it. - */ - my_work->fn = NULL; - continue; - } - if (my_work->fn == NULL) { - printk("pdflush: bogus wakeup\n"); - continue; - } - spin_unlock_irq(&pdflush_lock); - - (*my_work->fn)(my_work->arg0); - - spin_lock_irq(&pdflush_lock); - - /* - * Thread creation: For how long have there been zero - * available threads? - * - * To throttle creation, we reset last_empty_jifs. - */ - if (time_after(jiffies, last_empty_jifs + 1 * HZ)) { - if (list_empty(&pdflush_list) && - nr_pdflush_threads < nr_pdflush_threads_max) { - last_empty_jifs = jiffies; - nr_pdflush_threads++; - spin_unlock_irq(&pdflush_lock); - start_one_pdflush_thread(); - spin_lock_irq(&pdflush_lock); - } - } - - my_work->fn = NULL; - - /* - * Thread destruction: For how long has the sleepiest - * thread slept? - */ - if (list_empty(&pdflush_list)) - continue; - if (nr_pdflush_threads <= nr_pdflush_threads_min) - continue; - pdf = list_entry(pdflush_list.prev, struct pdflush_work, list); - if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) { - /* Limit exit rate */ - pdf->when_i_went_to_sleep = jiffies; - break; /* exeunt */ - } - } - nr_pdflush_threads--; - spin_unlock_irq(&pdflush_lock); - return 0; -} - -/* - * Of course, my_work wants to be just a local in __pdflush(). It is - * separated out in this manner to hopefully prevent the compiler from - * performing unfortunate optimisations against the auto variables. Because - * these are visible to other tasks and CPUs. (No problem has actually - * been observed. This is just paranoia). - */ -static int pdflush(void *dummy) -{ - struct pdflush_work my_work; - cpumask_var_t cpus_allowed; - - /* - * Since the caller doesn't even check kthread_run() worked, let's not - * freak out too much if this fails. - */ - if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { - printk(KERN_WARNING "pdflush failed to allocate cpumask\n"); - return 0; - } - - /* - * pdflush can spend a lot of time doing encryption via dm-crypt. We - * don't want to do that at keventd's priority. - */ - set_user_nice(current, 0); - - /* - * Some configs put our parent kthread in a limited cpuset, - * which kthread() overrides, forcing cpus_allowed == cpu_all_mask. - * Our needs are more modest - cut back to our cpusets cpus_allowed. - * This is needed as pdflush's are dynamically created and destroyed. - * The boottime pdflush's are easily placed w/o these 2 lines. - */ - cpuset_cpus_allowed(current, cpus_allowed); - set_cpus_allowed_ptr(current, cpus_allowed); - free_cpumask_var(cpus_allowed); - - return __pdflush(&my_work); -} - -/* - * Attempt to wake up a pdflush thread, and get it to do some work for you. - * Returns zero if it indeed managed to find a worker thread, and passed your - * payload to it. - */ -int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0) -{ - unsigned long flags; - int ret = 0; - - BUG_ON(fn == NULL); /* Hard to diagnose if it's deferred */ - - spin_lock_irqsave(&pdflush_lock, flags); - if (list_empty(&pdflush_list)) { - ret = -1; - } else { - struct pdflush_work *pdf; - - pdf = list_entry(pdflush_list.next, struct pdflush_work, list); - list_del_init(&pdf->list); - if (list_empty(&pdflush_list)) - last_empty_jifs = jiffies; - pdf->fn = fn; - pdf->arg0 = arg0; - wake_up_process(pdf->who); - } - spin_unlock_irqrestore(&pdflush_lock, flags); - - return ret; -} - -static void start_one_pdflush_thread(void) -{ - struct task_struct *k; - - k = kthread_run(pdflush, NULL, "pdflush"); - if (unlikely(IS_ERR(k))) { - spin_lock_irq(&pdflush_lock); - nr_pdflush_threads--; - spin_unlock_irq(&pdflush_lock); - } -} - -static int __init pdflush_init(void) -{ - int i; - - /* - * Pre-set nr_pdflush_threads... If we fail to create, - * the count will be decremented. - */ - nr_pdflush_threads = nr_pdflush_threads_min; - - for (i = 0; i < nr_pdflush_threads_min; i++) - start_one_pdflush_thread(); - return 0; -} - -module_init(pdflush_init); -- 1.6.2.2.446.gfbdc0