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authorAlexey Dobriyan <adobriyan@gmail.com>2009-03-31 15:23:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-01 08:59:13 -0700
commit704503d836042d4a4c7685b7036e7de0418fbc0f (patch)
tree218bea088f0b286981221e44d5247dab98020d30 /mm/page-writeback.c
parent6a11f75b6a17b5d9ac5025f8d048382fd1f47377 (diff)
downloadlwn-704503d836042d4a4c7685b7036e7de0418fbc0f.tar.gz
lwn-704503d836042d4a4c7685b7036e7de0418fbc0f.zip
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>
Diffstat (limited to 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 6aa92b03c747..30351f0063ac 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -92,14 +92,14 @@ int vm_dirty_ratio = 20;
unsigned long vm_dirty_bytes;
/*
- * The interval between `kupdate'-style writebacks, in jiffies
+ * The interval between `kupdate'-style writebacks
*/
-int dirty_writeback_interval = 5 * HZ;
+unsigned int dirty_writeback_interval = 5 * 100; /* sentiseconds */
/*
- * The longest number of jiffies for which data is allowed to remain dirty
+ * The longest time for which data is allowed to remain dirty
*/
-int dirty_expire_interval = 30 * HZ;
+unsigned int dirty_expire_interval = 30 * 100; /* sentiseconds */
/*
* Flag that makes the machine dump writes/reads and block dirtyings.
@@ -770,9 +770,9 @@ static void wb_kupdate(unsigned long arg)
sync_supers();
- oldest_jif = jiffies - dirty_expire_interval;
+ oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval);
start_jif = jiffies;
- next_jif = start_jif + dirty_writeback_interval;
+ next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
nr_to_write = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
@@ -801,9 +801,10 @@ static void wb_kupdate(unsigned long arg)
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
- proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
+ proc_dointvec(table, write, file, buffer, length, ppos);
if (dirty_writeback_interval)
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
+ mod_timer(&wb_timer, jiffies +
+ msecs_to_jiffies(dirty_writeback_interval * 10));
else
del_timer(&wb_timer);
return 0;
@@ -905,7 +906,8 @@ void __init page_writeback_init(void)
{
int shift;
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
+ mod_timer(&wb_timer,
+ jiffies + msecs_to_jiffies(dirty_writeback_interval * 10));
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);