On Wed, 19 Feb 2020 12:01:23 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 18 Feb 2020 17:44:26 -0800 Minchan Kim <minchan@xxxxxxxxxx> wrote: > > > Now, we have MADV_PAGEOUT and MADV_COLD as madvise hinting API. With that, > > application could give hints to kernel what memory range are preferred to be > > reclaimed. However, in some platform(e.g., Android), the information > > required to make the hinting decision is not known to the app. > > Instead, it is known to a centralized userspace daemon(e.g., ActivityManagerService), > > and that daemon must be able to initiate reclaim on its own without any app > > involvement. > > > > This patchset doesn't seem to be getting a lot of interest from other > potential users? It seems very specialized. Are there or will there > ever be any users of this apart from one Android daemon? > > Also, it doesn't terribly hard for ActivityManagerService to tell > another process "now run madvise with these arguments". Please explain > why this is not practical in ActivityManagerService and also within > other potential users of this syscall. I personally have interest in and hope successful development/merge of this patchset. The interested usecases of 'madvise_process()' for me is optimizations of general memory-intensive workloads having dynamic data access patterns on hierarchical memory systems (e.g., multi-tier memory or fast storage based swap devices). In more detail, I'm already using a part of this patchset for my RFC patchset implementing Data Access Monitoring-based Operation Schemes[1]. For my specific case, I don't need new system call but only target task argument, though. Once in a past, before joining my current company, I tried using 'madvise()' to optimize some scientific HPC programs. The improvement results were clear, but optimizing each of the workloads was challenging and time-consuming. I believe this new systemcall to be very helpful for such cases, either. [1] https://lore.kernel.org/linux-mm/20200218085309.18346-1-sjpark@xxxxxxxxxx/ Thanks, SeongJae Park
