On Mon, 2016-04-04 at 09:20 -0600, Chris Friesen wrote: > On 04/02/2016 07:15 PM, Nicholas A. Bellinger wrote: > > On Fri, 2016-04-01 at 12:35 -0600, Chris Friesen wrote: > > >>>> On a slightly different note, is there any way to throttle or limit the overall > >>>> bandwidth consumed by the iSCSI target in the kernel? I'd like to ensure that > >>>> the iSCSI traffic doesn't completely swamp the host accesses to the same block > >>>> device. > >>>> > >>>> I suppose I could do networking-based traffic shaping, but are there any > >>>> controls in the block IO subsystem? > >>>> > >>> > >>> On a individual block_device backend basis, block cgroups is the > >>> preferred method for doing this. > >>> > >>> Note that any rate limiting imposed by block cgroups is subject to the > >>> current se_node_acl->queue_depth enforced across all LUNs within a given > >>> iscsi session. > >> > >> > >> How would I use cgroups with the kernel iSCSI target? Is there a set of kernel > >> threads dedicated to the iSCSI target that I can assign to a particular group? > >> > > > > block cgroups can set I/O throttling (bandwidth + IOPs) limits for any > > normal struct block_device. > > > > These values are configured via blkio.throttle.* resource class, and the > > limits are imposed independently of the block_device's association with > > target_core_mod backend driver export. Namely: > > > > blkio.throttle.write_iops_device > > blkio.throttle.read_iops_device > > blkio.throttle.write_bps_device > > blkio.throttle.read_bdp_device > > > > Some examples using these values, plus more blkio.* info is here: > > http://events.linuxfoundation.org/sites/events/files/slides/cgroups_0.pdf. > > > > I understand how to set up the cgroups, but don't I need to ensure that the IO > operations happen in the context of a particular cgroup? If so, how do I ensure > that the in-kernel iSCSI target traffic happens in the context of the specified > group? Are there a set of kernel threads dedicated to processing iSCSI requests? > block cgroups does I/O ratelimiting at struct block_device level. Eg: The process cgroup (which AFAICT is what your thinking about) is separate from block cgroups, and doesn't need to be explicitly enabled in order for block cgroup to function. -- 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
