On Nov 04, 2008 11:10 -0500, Josef Bacik wrote: > somebody does a sync write or an fsync() traditionally we would sleep for 1 > jiffies, which depending on the value of HZ could be a significant amount of > time compared to how long it takes to commit a transaction to the underlying > storage. With this patch instead of sleeping for a jiffie, we check to see if > the amount of time this transaction has been running is less than the average > commit time, and if it is we sleep for the delta using schedule_hrtimeout to > give us a higher precision sleep time. This greatly benefits high end storage > where you could end up sleeping for longer than it takes to commit the > transaction and therefore sitting idle instead of allowing the transaction to > be committed by keeping the sleep time to a minimum so you are sure to always > be doing something. There was no reply to my previous comments about making the maximum sleep time be a fixed value (e.g. 15ms) instead of having it arbitrarily based on the jiffies value, which may change between 1ms and 10ms. I don't object to this being included in ext4, but I suspect it could do even better, or at least be more consistent than depending on the HZ value. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
