Hello, On Thu, Jan 5, 2012 at 8:19 PM, Shaohua Li <shaohua.li@xxxxxxxxx> wrote: >> For detailed discussion of the bug: >> >> http://thread.gmane.org/gmane.linux.kernel.next/20064/focus=20159 >> > this is overkill. when plug is added, we found huge performance > regression, that's why we add INSERT_SORT_MERGE. With what workload? I suspect most of the improvements is from merging across different cfqqs, no? The whole recursive thing can't be very useful if cross-cfqq merging isn't allowed. Maybe there are specific cases where last_merge hint merging can be specially effective. I don't know. Regardless, this is an apparent bug and the block tree will be pushed mainline pretty soon. If necessary, fix it better later. Doing complex things inside merge window usually isn't a good idea. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
