On Thu, 15 Nov 2012, Anton Vorontsov wrote: > Hehe, you're saying that we have to have cgroups=y. :) But some folks were > deliberately asking us to make the cgroups optional. > Enabling just CONFIG_CGROUPS (which is enabled by default) and no other current cgroups increases the size of the kernel text by less than 0.3% with x86_64 defconfig: text data bss dec hex filename 10330039 1038912 1118208 12487159 be89f7 vmlinux.disabled 10360993 1041624 1122304 12524921 bf1d79 vmlinux.enabled I understand that users with minimally-enabled configs for an optimized memory footprint will have a higher percentage because their kernel is already smaller (~1.8% increase for allnoconfig), but I think the cost of enabling the cgroups code to be able to mount a vmpressure cgroup (which I'd rename to be "mempressure" to be consistent with "memcg" but it's only an opinion) is relatively small and allows for a much more maintainable and extendable feature to be included: it already provides the cgroup.event_control interface that supports eventfd that makes implementation much easier. It also makes writing a library on top of the cgroup to be much easier because of the standardization. I'm more concerned about what to do with the memcg memory thresholds and whether they can be replaced with this new cgroup. If so, then we'll have to figure out how to map those triggers to use the new cgroup's interface in a way that doesn't break current users that open and pass the fd of memory.usage_in_bytes to cgroup.event_control for memcg. > OK, here is what I can try to do: > > - Implement memory pressure cgroup as you described, by doing so we'd make > the thing play well with cpusets and memcg; > > - This will be eventfd()-based; > Should be based on cgroup.event_control, see how memcg interfaces its memory thresholds with this in Documentation/cgroups/memory.txt. > - Once done, we will have a solution for pretty much every major use-case > (i.e. servers, desktops and Android, they all have cgroups enabled); > Excellent! I'd be interested in hearing anybody else's opinions, especially those from the memcg world, so we make sure that everybody is happy with the API that you've described. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
