Messages in this thread | | | Date | Thu, 11 Feb 2016 17:28:24 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH RFC 10/22] block, bfq: add full hierarchical scheduling and cgroups support |
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Hello,
On Mon, Feb 01, 2016 at 11:12:46PM +0100, Paolo Valente wrote: > From: Arianna Avanzini <avanzini.arianna@gmail.com> > > Complete support for full hierarchical scheduling, with a cgroups > interface. The name of the added policy is bfq. > > Weights can be assigned explicitly to groups and processes through the > cgroups interface, differently from what happens, for single > processes, if the cgroups interface is not used (as explained in the > description of the previous patch). In particular, since each node has > a full scheduler, each group can be assigned its own weight.
* It'd be great if how cgroup support is achieved is better documented.
* How's writeback handled?
* After all patches are applied, both CONFIG_BFQ_GROUP_IOSCHED and CONFIG_CFQ_GROUP_IOSCHED exist.
* The default weight and weight range don't seem to follow the defined interface on the v2 hierarchy. The default value should be 100.
* With all patches applied, booting triggers a RCU context warning. Please build with lockdep and RCU debugging turned on and fix the issue.
* I was testing on the v2 hierarchy with two top-level cgroups one hosting sequential workload and the other completely random. While they eventually converged to a reasonable state, starting up the sequential workload while the random workload was running was extremely slow. It crawled for quite a while.
* And "echo 100 > io.weight" hung the writing process.
Thanks.
-- tejun
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