On Tue, Mar 10, 2020 at 03:20:08PM -0700, Minchan Kim wrote: > On Thu, Mar 05, 2020 at 07:15:10PM +0100, Vlastimil Babka wrote: > > On 3/2/20 8:36 PM, Minchan Kim wrote: > > > There is usecase that System Management Software(SMS) want to give > > > a memory hint like MADV_[COLD|PAGEEOUT] to other processes and > > > in the case of Android, it is the ActivityManagerService. > > > > > > It's similar in spirit to madvise(MADV_WONTNEED), but the information > > > > You mean MADV_DONTNEED? > > Mean to DONT_NEED's future version. > > > > > > required to make the reclaim decision is not known to the app. > > > > This seems to be mixing up the differences between MADV_DONTNEED and > > COLD/PAGEOUT and self-imposed vs external memory hints? > > Sorry, I don't understand what you want here. > > > > > > Instead, > > > it is known to the centralized userspace daemon(ActivityManagerService), > > > and that daemon must be able to initiate reclaim on its own without > > > any app involvement. > > > > > > To solve the issue, this patch introduces a new syscall process_madvise(2). > > > It uses pidfd of an external process to give the hint. > > > > > > int process_madvise(int pidfd, void *addr, size_t length, int advise, > > > unsigned long flag); > > > > It's more common to call the argument 'flags' not 'flag'? The code seems to call > > it flags. Also in line with madvise(2), the 'advise' argument should rather be > > 'advice'. This is more important for the manpage, but let's be consistent. > > Yub, I will send the patch along with your comment in previous patch. Only place to use *advice* in kernel is comment in madvise_willneed. Al other places use advise in kernel so I wanted to be more consistent with other kernel sources. For man page, we could use the term "advice", no problem.
