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https://github.com/Fishwaldo/linux-bl808.git
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7ccb9ad536
Control the pause time and the call intervals to balance_dirty_pages() with three parameters: 1) max_pause, limited by bdi_dirty and MAX_PAUSE 2) the target pause time, grows with the number of dd tasks and is normally limited by max_pause/2 3) the minimal pause, set to half the target pause and is used to skip short sleeps and accumulate them into bigger ones The typical behaviors after patch: - if ever task_ratelimit is far below dirty_ratelimit, the pause time will remain constant at max_pause and nr_dirtied_pause will be fluctuating with task_ratelimit - in the normal cases, nr_dirtied_pause will remain stable (keep in the same pace with dirty_ratelimit) and the pause time will be fluctuating with task_ratelimit In summary, someone has to fluctuate with task_ratelimit, because task_ratelimit = nr_dirtied_pause / pause We normally prefer a stable nr_dirtied_pause, until reaching max_pause. The notable behavior changes are: - in stable workloads, there will no longer be sudden big trajectory switching of nr_dirtied_pause as concerned by Peter. It will be as smooth as dirty_ratelimit and changing proportionally with it (as always, assuming bdi bandwidth does not fluctuate across 2^N lines, otherwise nr_dirtied_pause will show up in 2+ parallel trajectories) - in the rare cases when something keeps task_ratelimit far below dirty_ratelimit, the smoothness can no longer be retained and nr_dirtied_pause will be "dancing" with task_ratelimit. This fixes a (not that destructive but still not good) bug that dirty_ratelimit gets brought down undesirably <= balanced_dirty_ratelimit is under estimated <= weakly executed task_ratelimit <= pause goes too large and gets trimmed down to max_pause <= nr_dirtied_pause (based on dirty_ratelimit) is set too large <= dirty_ratelimit being much larger than task_ratelimit - introduce min_pause to avoid small pause sleeps - when pause is trimmed down to max_pause, try to compensate it at the next pause time The "refactor" type of changes are: The max_pause equation is slightly transformed to make it slightly more efficient. We now scale target_pause by (N * 10ms) on 2^N concurrent tasks, which is effectively equal to the original scaling max_pause by (N * 20ms) because the original code does implicit target_pause ~= max_pause / 2. Based on the same implicit ratio, target_pause starts with 10ms on 1 dd. CC: Jan Kara <jack@suse.cz> CC: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> |
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| .. | ||
| backing-dev.c | ||
| bootmem.c | ||
| bounce.c | ||
| cleancache.c | ||
| compaction.c | ||
| debug-pagealloc.c | ||
| dmapool.c | ||
| fadvise.c | ||
| failslab.c | ||
| filemap.c | ||
| filemap_xip.c | ||
| fremap.c | ||
| highmem.c | ||
| huge_memory.c | ||
| hugetlb.c | ||
| hwpoison-inject.c | ||
| init-mm.c | ||
| internal.h | ||
| Kconfig | ||
| Kconfig.debug | ||
| kmemcheck.c | ||
| kmemleak-test.c | ||
| kmemleak.c | ||
| ksm.c | ||
| maccess.c | ||
| madvise.c | ||
| Makefile | ||
| memblock.c | ||
| memcontrol.c | ||
| memory-failure.c | ||
| memory.c | ||
| memory_hotplug.c | ||
| mempolicy.c | ||
| mempool.c | ||
| migrate.c | ||
| mincore.c | ||
| mlock.c | ||
| mm_init.c | ||
| mmap.c | ||
| mmu_context.c | ||
| mmu_notifier.c | ||
| mmzone.c | ||
| mprotect.c | ||
| mremap.c | ||
| msync.c | ||
| nobootmem.c | ||
| nommu.c | ||
| oom_kill.c | ||
| page-writeback.c | ||
| page_alloc.c | ||
| page_cgroup.c | ||
| page_io.c | ||
| page_isolation.c | ||
| pagewalk.c | ||
| percpu-km.c | ||
| percpu-vm.c | ||
| percpu.c | ||
| pgtable-generic.c | ||
| prio_tree.c | ||
| process_vm_access.c | ||
| quicklist.c | ||
| readahead.c | ||
| rmap.c | ||
| shmem.c | ||
| slab.c | ||
| slob.c | ||
| slub.c | ||
| sparse-vmemmap.c | ||
| sparse.c | ||
| swap.c | ||
| swap_state.c | ||
| swapfile.c | ||
| thrash.c | ||
| truncate.c | ||
| util.c | ||
| vmalloc.c | ||
| vmscan.c | ||
| vmstat.c | ||