On Sat, 21 Oct 2000, Bill Wendling wrote:

> } > bdflush is broken in current kernels.  I posted to linux-mm about this,
> } > but Rik et al haven't shown any interest.  I normally see bursts of 
> } > up to around 40K cs/second when doing writes; I hacked a little 
> } > premption counter into the kernel and verified that they're practially
> } > all bdflush...
> } 
> There's some strangness in bdflush(). The comment says:
> 
>                 /*
>                  * If there are still a lot of dirty buffers around,
>                  * skip the sleep and flush some more. Otherwise, we
>                  * go to sleep waiting a wakeup.
>                  */
>                 if (!flushed || balance_dirty_state(NODEV) < 0) {
>                         run_task_queue(&tq_disk);
>                         schedule();
>                 }

Speaking of bdflush brokenness, I was trying to tune it using
/proc/sys/vm/bdflush. I was trying to eliminate the bursty write behaviour
Linux always seems to have had (exhibited by e.g. find /).

Unfortunately, different /proc/sys/vm/bdflush settings didn't seem to have
much (if any) effect. Is this another case of /proc/sys/vm/* settings
being ignored? If so they should be removed.

I was hoping to get a steady trickle of writes instead of the occasional
mammoth burst.

Cheers
Chris

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