Re: [PATCH v16 10/16] x86/sgx: Implement async reclamation for cgroup

["Jarkko Sakkinen" <jarkko@kernel.org>]

On Wed Aug 21, 2024 at 4:53 AM EEST, Haitao Huang wrote:
> From: Kristen Carlson Accardi <kristen@linux.intel.com>
>
> In cases EPC pages need be allocated during a page fault and the cgroup
> usage is near its limit, an asynchronous reclamation needs to be
> triggered to avoid blocking the page fault handling.
>
> To keep implementation simple, use a workqueue instead of kthread to
> schedule the asynchronous reclamation work. Add corresponding work item and
> function definitions for EPC cgroup.
>
> In sgx_cgroup_try_charge(), if caller does not allow synchronous
> reclamation, queue an asynchronous work into the workqueue.
>
> The current global reclaimer, ksgxd, maintains a threshold for the
> minimal free EPC pages to avoid thrashing when allocating EPC pages.
> Similarly, only reclaiming EPC pages from the current cgroup when its
> usage actually reaches limit could also cause thrashing.  To avoid that,
> define a similar "per-cgroup usage threshold" and actively trigger
> asynchronous per-cgroup EPC reclamation when the usage reaches the
> threshold after try_charge() is successful.
>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
> Co-developed-by: Haitao Huang <haitao.huang@linux.intel.com>
> Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
> Tested-by: Jarkko Sakkinen <jarkko@kernel.org>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko