mm: fix proc_dointvec_userhz_jiffies "breakage"
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=9838 On i386, HZ=1000, jiffies_to_clock_t() converts time in a somewhat strange way from the user's point of view: # echo 500 >/proc/sys/vm/dirty_writeback_centisecs # cat /proc/sys/vm/dirty_writeback_centisecs 499 So, we have 5000 jiffies converted to only 499 clock ticks and reported back. TICK_NSEC = 999848 ACTHZ = 256039 Keeping in-kernel variable in units passed from userspace will fix issue of course, but this probably won't be right for every sysctl. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -109,8 +109,8 @@ extern int dirty_background_ratio;
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extern unsigned long dirty_background_bytes;
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extern int vm_dirty_ratio;
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extern unsigned long vm_dirty_bytes;
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extern int dirty_writeback_interval;
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extern int dirty_expire_interval;
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extern unsigned int dirty_writeback_interval;
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extern unsigned int dirty_expire_interval;
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extern int vm_highmem_is_dirtyable;
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extern int block_dump;
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extern int laptop_mode;
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@ -1010,7 +1010,7 @@ static struct ctl_table vm_table[] = {
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.data = &dirty_expire_interval,
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.maxlen = sizeof(dirty_expire_interval),
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.mode = 0644,
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.proc_handler = &proc_dointvec_userhz_jiffies,
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.proc_handler = &proc_dointvec,
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},
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{
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.ctl_name = VM_NR_PDFLUSH_THREADS,
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@ -92,14 +92,14 @@ int vm_dirty_ratio = 20;
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unsigned long vm_dirty_bytes;
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/*
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* The interval between `kupdate'-style writebacks, in jiffies
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* The interval between `kupdate'-style writebacks
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*/
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int dirty_writeback_interval = 5 * HZ;
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unsigned int dirty_writeback_interval = 5 * 100; /* sentiseconds */
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/*
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* The longest number of jiffies for which data is allowed to remain dirty
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* The longest time for which data is allowed to remain dirty
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*/
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int dirty_expire_interval = 30 * HZ;
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unsigned int dirty_expire_interval = 30 * 100; /* sentiseconds */
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/*
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* Flag that makes the machine dump writes/reads and block dirtyings.
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@ -770,9 +770,9 @@ static void wb_kupdate(unsigned long arg)
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sync_supers();
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oldest_jif = jiffies - dirty_expire_interval;
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oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval);
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start_jif = jiffies;
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next_jif = start_jif + dirty_writeback_interval;
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next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
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nr_to_write = global_page_state(NR_FILE_DIRTY) +
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global_page_state(NR_UNSTABLE_NFS) +
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(inodes_stat.nr_inodes - inodes_stat.nr_unused);
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@ -801,9 +801,10 @@ static void wb_kupdate(unsigned long arg)
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int dirty_writeback_centisecs_handler(ctl_table *table, int write,
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struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
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{
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proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
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proc_dointvec(table, write, file, buffer, length, ppos);
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if (dirty_writeback_interval)
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mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
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mod_timer(&wb_timer, jiffies +
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msecs_to_jiffies(dirty_writeback_interval * 10));
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else
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del_timer(&wb_timer);
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return 0;
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@ -905,7 +906,8 @@ void __init page_writeback_init(void)
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{
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int shift;
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mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
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mod_timer(&wb_timer,
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jiffies + msecs_to_jiffies(dirty_writeback_interval * 10));
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writeback_set_ratelimit();
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register_cpu_notifier(&ratelimit_nb);
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