On Friday May 2, mbasil@alabanza.com wrote:
> Heh... that's funny. That last message stopped at a lone period on the line.
> :o) Here's the actual message.
>
>
>
> Hi Neil,
>
> I have a question regarding your bdflush settings. The kernel docs say the
> following:
>
>
>
> Table 2-2: Parameters in /proc/sys/vm/bdflush
> ..............................................................................
> Value Meaning
> nfract Percentage of buffer cache dirty to activate bdflush
> ndirty Maximum number of dirty blocks to write out per wake-cycle
> nrefill Number of clean buffers to try to obtain each time we call refill
> nref_dirt buffer threshold for activating bdflush when trying to refill
> buffers.
> dummy Unused
> age_buffer Time for normal buffer to age before we flush it
> age_super Time for superblock to age before we flush it
> dummy Unused
> dummy Unused
> ..............................................................................
>
>
But the kernel source says :
fs/buffer.c:
union bdflush_param {
struct {
int nfract; /* Percentage of buffer cache dirty to
activate bdflush */
int ndirty; /* Maximum number of dirty blocks to write out per
wake-cycle */
int dummy2; /* old "nrefill" */
int dummy3; /* unused */
int interval; /* jiffies delay between kupdate flushes */
int age_buffer; /* Time for normal buffer to age before we flush it */
int nfract_sync;/* Percentage of buffer cache dirty to
activate bdflush synchronously */
int nfract_stop_bdflush; /* Percetange of buffer cache dirty to stop bdflush */
int dummy5; /* unused */
} b_un;
unsigned int data[N_PARAM];
} bdf_prm = {{30, 500, 0, 0, 5*HZ, 30*HZ, 60, 20, 0}};
So the 5th number is 'interval'.
Later:
/* update interval */
interval = bdf_prm.b_un.interval;
if (interval) {
tsk->state = TASK_INTERRUPTIBLE;
schedule_timeout(interval);
} else {
stop_kupdate:
tsk->state = TASK_STOPPED;
schedule(); /* wait for SIGCONT */
}
so interval seems to actually be used. Maybe someone should update
the kernel docs..... but I just check the current kernel docs:
Documentation/filesystems/proc.txt
and
Documentation/sysctl/vm.txt
both from the current 2.4.latest tree and they seem to be correct.
NeilBrown
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