Messages in this thread | | | Date | Sat, 21 Oct 2000 21:35:02 +0100 (BST) | From | Chris Evans <> | Subject | Re: [patch(?)] question wrt context switching during disk i/o |
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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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