Disk blocks for long periods

[Dave Ellis]

joakim.tjernlund at lumentis.se said:

> hmm, I just noticed that the BIG kernel lock is held while 
> the erasing thread executes, since kupdate takes it in 
> sync_old_buffers() (if I understand this code correctly). 
> Maybe that is causing current->need_resched to be set?
> 
> Also, is it not a bad idea to hold the kernel lock for, 
> possibly, seconds while erasing sectors?

If it is doing that, it doesn't seem right to me. But I 
thought jffs2/mtd bypassed the kernel buffers, so maybe 
kupdate and sync_old_buffers() are not involved here? I don't
know much about this.
 
> I assume your chip does not support buffered writes? or is it 
> just do_write_one_word() that is causing the log delays?

No, it doesn't support buffered writes. The long delay I saw
comes from sleeping for a jiffie during each call to
do_write_oneword().

Dave Ellis
dge at sixnetio.com