Hi Andrew, It's the resend with fixing build errors kbuildbot reported. Please take it this version to get more test coverage. Thanks. On Fri, Jul 26, 2019 at 11:34:30AM +0900, Minchan Kim wrote: > This patch is part of previous series: > https://lore.kernel.org/lkml/20190531064313.193437-1-minchan@xxxxxxxxxx/ > Originally, it was created for external madvise hinting feature. > > https://lkml.org/lkml/2019/5/31/463 > Michal wanted to separte the discussion from external hinting interface > so this patchset includes only first part of my entire patchset > > - introduce MADV_COLD and MADV_PAGEOUT hint to madvise. > > However, I keep entire description for others for easier understanding > why this kinds of hint was born. > > Thanks. > > This patchset is against on mmotm-mmotm-2019-07-24-21-39. > > Below is description of previous entire patchset. > > ================= &< ===================== > > - Background > > The Android terminology used for forking a new process and starting an app > from scratch is a cold start, while resuming an existing app is a hot start. > While we continually try to improve the performance of cold starts, hot > starts will always be significantly less power hungry as well as faster so > we are trying to make hot start more likely than cold start. > > To increase hot start, Android userspace manages the order that apps should > be killed in a process called ActivityManagerService. ActivityManagerService > tracks every Android app or service that the user could be interacting with > at any time and translates that into a ranked list for lmkd(low memory > killer daemon). They are likely to be killed by lmkd if the system has to > reclaim memory. In that sense they are similar to entries in any other cache. > Those apps are kept alive for opportunistic performance improvements but > those performance improvements will vary based on the memory requirements of > individual workloads. > > - Problem > > Naturally, cached apps were dominant consumers of memory on the system. > However, they were not significant consumers of swap even though they are > good candidate for swap. Under investigation, swapping out only begins > once the low zone watermark is hit and kswapd wakes up, but the overall > allocation rate in the system might trip lmkd thresholds and cause a cached > process to be killed(we measured performance swapping out vs. zapping the > memory by killing a process. Unsurprisingly, zapping is 10x times faster > even though we use zram which is much faster than real storage) so kill > from lmkd will often satisfy the high zone watermark, resulting in very > few pages actually being moved to swap. > > - Approach > > The approach we chose was to use a new interface to allow userspace to > proactively reclaim entire processes by leveraging platform information. > This allowed us to bypass the inaccuracy of the kernel’s LRUs for pages > that are known to be cold from userspace and to avoid races with lmkd > by reclaiming apps as soon as they entered the cached state. Additionally, > it could provide many chances for platform to use much information to > optimize memory efficiency. > > To achieve the goal, the patchset introduce two new options for madvise. > One is MADV_COLD which will deactivate activated pages and the other is > MADV_PAGEOUT which will reclaim private pages instantly. These new options > complement MADV_DONTNEED and MADV_FREE by adding non-destructive ways to > gain some free memory space. MADV_PAGEOUT is similar to MADV_DONTNEED in a way > that it hints the kernel that memory region is not currently needed and > should be reclaimed immediately; MADV_COLD is similar to MADV_FREE in a way > that it hints the kernel that memory region is not currently needed and > should be reclaimed when memory pressure rises. > > * v6 - http://lore.kernel.org/lkml/20190723062539.198697-1-minchan@xxxxxxxxxx > * v5 - http://lore.kernel.org/lkml/20190714233401.36909-1-minchan@xxxxxxxxxx > * v4 - http://lore.kernel.org/lkml/20190711012528.176050-1-minchan@xxxxxxxxxx > * v3 - http://lore.kernel.org/lkml/20190627115405.255259-1-minchan@xxxxxxxxxx > * v2 - http://lore.kernel.org/lkml/20190610111252.239156-1-minchan@xxxxxxxxxx > * v1 - http://lore.kernel.org/lkml/20190603053655.127730-1-minchan@xxxxxxxxxx > > Minchan Kim (5): > mm: introduce MADV_COLD > mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM > mm: account nr_isolated_xxx in [isolate|putback]_lru_page > mm: introduce MADV_PAGEOUT > mm: factor out common parts between MADV_COLD and MADV_PAGEOUT > > arch/alpha/include/uapi/asm/mman.h | 3 + > arch/mips/include/uapi/asm/mman.h | 3 + > arch/parisc/include/uapi/asm/mman.h | 3 + > arch/xtensa/include/uapi/asm/mman.h | 3 + > include/linux/swap.h | 2 + > include/uapi/asm-generic/mman-common.h | 3 + > mm/compaction.c | 2 - > mm/gup.c | 7 +- > mm/internal.h | 2 +- > mm/khugepaged.c | 3 - > mm/madvise.c | 274 ++++++++++++++++++++++++- > mm/memory-failure.c | 3 - > mm/memory_hotplug.c | 4 - > mm/mempolicy.c | 3 - > mm/migrate.c | 37 +--- > mm/oom_kill.c | 2 +- > mm/swap.c | 42 ++++ > mm/vmscan.c | 83 +++++++- > 18 files changed, 416 insertions(+), 63 deletions(-) > > -- > 2.22.0.709.g102302147b-goog >
