On Wed, Jun 17, 2015 at 02:52:37PM -0400, Tejun Heo wrote: > > Hmmm... so, overriding things *before* an bio is issued shouldn't be > too difficult and as long as this sort of operations aren't prevalent > we might be able to get away with just charging them against root. > Especially if it's to avoid getting blocked on the journal which we > already consider a shared overhead which is charged to root. If this > becomes large enough to require exacting charges, it'll be more > complex but still way better than trying to raise priority on a bio > which is already issued, which is likely to be excruciatingly painful > if possible at all. Yeah, just charging the overhead to root seems good enough. I could imagine charging it to whatever cgroup the jbd/jbd2 thread belongs to, which in turn would be the cgroup of the process that mounted the file system. The only problem with that is that if a low-priority process is allowed to mount a file system, and it gets traversed by a high priority process, the high priority process will get impacted. So maybe it's better to just say that it always get charged to the root cgroup. - Ted -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
