diff options
| author |   Dennis Zhou <dennis@kernel.org> | 2019-02-25 09:03:50 -0800 |
|---|---|---|
| committer | Dennis Zhou <dennis@kernel.org> | 2019-03-13 12:25:31 -0700 |
| commit | 8744d859427c6198dce490619809754336954297 (patch) | |
| tree | 4d0a28eaac997430e93821ed4c6b82bb66b9a4f4 /mm/percpu.c | |
| parent | percpu: manage chunks based on contig_bits instead of free_bytes (diff) | |
| download | wireguard-linux-8744d859427c6198dce490619809754336954297.tar.xz wireguard-linux-8744d859427c6198dce490619809754336954297.zip | |
percpu: relegate chunks unusable when failing small allocations
In certain cases, requestors of percpu memory may want specific
alignments. However, it is possible to end up in situations where the
contig_hint matches, but the alignment does not. This causes excess
scanning of chunks that will fail. To prevent this, if a small
allocation fails (< 32B), the chunk is moved to the empty list. Once an
allocation is freed from that chunk, it is placed back into rotation.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Diffstat (limited to 'mm/percpu.c')
| -rw-r--r-- | mm/percpu.c | 35 |
1 files changed, 26 insertions, 9 deletions
diff --git a/mm/percpu.c b/mm/percpu.c index fc1e8efb5222..2c1a9a2ca13b 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -94,6 +94,8 @@ /* the slots are sorted by free bytes left, 1-31 bytes share the same slot */ #define PCPU_SLOT_BASE_SHIFT 5 +/* chunks in slots below this are subject to being sidelined on failed alloc */ +#define PCPU_SLOT_FAIL_THRESHOLD 3 #define PCPU_EMPTY_POP_PAGES_LOW 2 #define PCPU_EMPTY_POP_PAGES_HIGH 4 @@ -488,6 +490,22 @@ static void pcpu_mem_free(void *ptr) kvfree(ptr); } +static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot, + bool move_front) +{ + if (chunk != pcpu_reserved_chunk) { + if (move_front) + list_move(&chunk->list, &pcpu_slot[slot]); + else + list_move_tail(&chunk->list, &pcpu_slot[slot]); + } +} + +static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot) +{ + __pcpu_chunk_move(chunk, slot, true); +} + /** * pcpu_chunk_relocate - put chunk in the appropriate chunk slot * @chunk: chunk of interest @@ -505,12 +523,8 @@ static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot) { int nslot = pcpu_chunk_slot(chunk); - if (chunk != pcpu_reserved_chunk && oslot != nslot) { - if (oslot < nslot) - list_move(&chunk->list, &pcpu_slot[nslot]); - else - list_move_tail(&chunk->list, &pcpu_slot[nslot]); - } + if (oslot != nslot) + __pcpu_chunk_move(chunk, nslot, oslot < nslot); } /** @@ -1395,7 +1409,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL; bool do_warn = !(gfp & __GFP_NOWARN); static int warn_limit = 10; - struct pcpu_chunk *chunk; + struct pcpu_chunk *chunk, *next; const char *err; int slot, off, cpu, ret; unsigned long flags; @@ -1457,11 +1471,14 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, restart: /* search through normal chunks */ for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) { - list_for_each_entry(chunk, &pcpu_slot[slot], list) { + list_for_each_entry_safe(chunk, next, &pcpu_slot[slot], list) { off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic); - if (off < 0) + if (off < 0) { + if (slot < PCPU_SLOT_FAIL_THRESHOLD) + pcpu_chunk_move(chunk, 0); continue; + } off = pcpu_alloc_area(chunk, bits, bit_align, off); if (off >= 0) |