Messages in this thread | | | Date | Mon, 30 May 2022 22:41:30 -0400 | Subject | Re: [PATCH v5 00/11] Use obj_cgroup APIs to charge the LRU pages | From | Waiman Long <> |
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On 5/30/22 03:49, Muchun Song wrote: > This version is rebased on v5.18. > > Since the following patchsets applied. All the kernel memory are charged > with the new APIs of obj_cgroup. > > [v17,00/19] The new cgroup slab memory controller [1] > [v5,0/7] Use obj_cgroup APIs to charge kmem pages [2] > > But user memory allocations (LRU pages) pinning memcgs for a long time - > it exists at a larger scale and is causing recurring problems in the real > world: page cache doesn't get reclaimed for a long time, or is used by the > second, third, fourth, ... instance of the same job that was restarted into > a new cgroup every time. Unreclaimable dying cgroups pile up, waste memory, > and make page reclaim very inefficient. > > We can convert LRU pages and most other raw memcg pins to the objcg direction > to fix this problem, and then the LRU pages will not pin the memcgs. > > This patchset aims to make the LRU pages to drop the reference to memory > cgroup by using the APIs of obj_cgroup. Finally, we can see that the number > of the dying cgroups will not increase if we run the following test script. > > ```bash > #!/bin/bash > > dd if=/dev/zero of=temp bs=4096 count=1 > cat /proc/cgroups | grep memory > > for i in {0..2000} > do > mkdir /sys/fs/cgroup/memory/test$i > echo $$ > /sys/fs/cgroup/memory/test$i/cgroup.procs > cat temp >> log > echo $$ > /sys/fs/cgroup/memory/cgroup.procs > rmdir /sys/fs/cgroup/memory/test$i > done > > cat /proc/cgroups | grep memory > > rm -f temp log > ``` > > [1] https://lore.kernel.org/linux-mm/20200623015846.1141975-1-guro@fb.com/ > [2] https://lore.kernel.org/linux-mm/20210319163821.20704-1-songmuchun@bytedance.com/ > > v4: https://lore.kernel.org/all/20220524060551.80037-1-songmuchun@bytedance.com/ > v3: https://lore.kernel.org/all/20220216115132.52602-1-songmuchun@bytedance.com/ > v2: https://lore.kernel.org/all/20210916134748.67712-1-songmuchun@bytedance.com/ > v1: https://lore.kernel.org/all/20210814052519.86679-1-songmuchun@bytedance.com/ > RFC v4: https://lore.kernel.org/all/20210527093336.14895-1-songmuchun@bytedance.com/ > RFC v3: https://lore.kernel.org/all/20210421070059.69361-1-songmuchun@bytedance.com/ > RFC v2: https://lore.kernel.org/all/20210409122959.82264-1-songmuchun@bytedance.com/ > RFC v1: https://lore.kernel.org/all/20210330101531.82752-1-songmuchun@bytedance.com/ > > v5: > - Lots of improvements from Johannes, Roman and Waiman. > - Fix lockdep warning reported by kernel test robot. > - Add two new patches to do code cleanup. > - Collect Acked-by and Reviewed-by from Johannes and Roman. > - I didn't replace local_irq_disable/enable() to local_lock/unlock_irq() since > local_lock/unlock_irq() takes an parameter, it needs more thinking to transform > it to local_lock. It could be an improvement in the future.
My comment about local_lock/unlock is just a note that local_irq_disable/enable() have to be eventually replaced. However, we need to think carefully where to put the newly added local_lock. It is perfectly fine to keep it as is and leave the conversion as a future follow-up.
Thank you very much for your work on this patchset.
Cheers, Longman
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