> -----Original Message----- > From: owner-linux-mm@xxxxxxxxx [mailto:owner-linux-mm@xxxxxxxxx] On > Behalf Of Dennis Zhou > Sent: 2019年2月28日 10:19 > To: Dennis Zhou <dennis@xxxxxxxxxx>; Tejun Heo <tj@xxxxxxxxxx>; Christoph > Lameter <cl@xxxxxxxxx> > Cc: Vlad Buslov <vladbu@xxxxxxxxxxxx>; kernel-team@xxxxxx; > linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: [PATCH 11/12] percpu: convert chunk hints to be based on > pcpu_block_md > > As mentioned in the last patch, a chunk's hints are no different than a block > just responsible for more bits. This converts chunk level hints to use a > pcpu_block_md to maintain them. This lets us reuse the same hint helper > functions as a block. The left_free and right_free are unused by the chunk's > pcpu_block_md. > > Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx> > --- > mm/percpu-internal.h | 5 +- > mm/percpu-stats.c | 5 +- > mm/percpu.c | 120 +++++++++++++++++++------------------------ > 3 files changed, 57 insertions(+), 73 deletions(-) > > diff --git a/mm/percpu-internal.h b/mm/percpu-internal.h index > 119bd1119aa7..0468ba500bd4 100644 > --- a/mm/percpu-internal.h > +++ b/mm/percpu-internal.h > @@ -39,9 +39,7 @@ struct pcpu_chunk { > > struct list_head list; /* linked to pcpu_slot lists */ > int free_bytes; /* free bytes in the chunk */ > - int contig_bits; /* max contiguous size hint */ > - int contig_bits_start; /* contig_bits starting > - offset */ > + struct pcpu_block_md chunk_md; > void *base_addr; /* base address of this chunk */ > > unsigned long *alloc_map; /* allocation map */ > @@ -49,7 +47,6 @@ struct pcpu_chunk { > struct pcpu_block_md *md_blocks; /* metadata blocks */ > > void *data; /* chunk data */ > - int first_bit; /* no free below this */ > bool immutable; /* no [de]population allowed */ > int start_offset; /* the overlap with the previous > region to have a page aligned > diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c index > b5fdd43b60c9..ef5034a0464e 100644 > --- a/mm/percpu-stats.c > +++ b/mm/percpu-stats.c > @@ -53,6 +53,7 @@ static int find_max_nr_alloc(void) static void > chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk, > int *buffer) > { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > int i, last_alloc, as_len, start, end; > int *alloc_sizes, *p; > /* statistics */ > @@ -121,9 +122,9 @@ static void chunk_map_stats(struct seq_file *m, > struct pcpu_chunk *chunk, > P("nr_alloc", chunk->nr_alloc); > P("max_alloc_size", chunk->max_alloc_size); > P("empty_pop_pages", chunk->nr_empty_pop_pages); > - P("first_bit", chunk->first_bit); > + P("first_bit", chunk_md->first_free); > P("free_bytes", chunk->free_bytes); > - P("contig_bytes", chunk->contig_bits * PCPU_MIN_ALLOC_SIZE); > + P("contig_bytes", chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE); > P("sum_frag", sum_frag); > P("max_frag", max_frag); > P("cur_min_alloc", cur_min_alloc); > diff --git a/mm/percpu.c b/mm/percpu.c > index 7cdf14c242de..197479f2c489 100644 > --- a/mm/percpu.c > +++ b/mm/percpu.c > @@ -233,10 +233,13 @@ static int pcpu_size_to_slot(int size) > > static int pcpu_chunk_slot(const struct pcpu_chunk *chunk) { > - if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || chunk->contig_bits > == 0) > + const struct pcpu_block_md *chunk_md = &chunk->chunk_md; > + > + if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE || > + chunk_md->contig_hint == 0) > return 0; > > - return pcpu_size_to_slot(chunk->contig_bits * PCPU_MIN_ALLOC_SIZE); > + return pcpu_size_to_slot(chunk_md->contig_hint * > PCPU_MIN_ALLOC_SIZE); > } > > /* set the pointer to a chunk in a page struct */ @@ -592,54 +595,6 @@ > static inline bool pcpu_region_overlap(int a, int b, int x, int y) > return false; > } > > -/** > - * pcpu_chunk_update - updates the chunk metadata given a free area > - * @chunk: chunk of interest > - * @bit_off: chunk offset > - * @bits: size of free area > - * > - * This updates the chunk's contig hint and starting offset given a free area. > - * Choose the best starting offset if the contig hint is equal. > - */ > -static void pcpu_chunk_update(struct pcpu_chunk *chunk, int bit_off, int bits) > -{ > - if (bits > chunk->contig_bits) { > - chunk->contig_bits_start = bit_off; > - chunk->contig_bits = bits; > - } else if (bits == chunk->contig_bits && chunk->contig_bits_start && > - (!bit_off || > - __ffs(bit_off) > __ffs(chunk->contig_bits_start))) { > - /* use the start with the best alignment */ > - chunk->contig_bits_start = bit_off; > - } > -} > - > -/** > - * pcpu_chunk_refresh_hint - updates metadata about a chunk > - * @chunk: chunk of interest > - * > - * Iterates over the metadata blocks to find the largest contig area. > - * It also counts the populated pages and uses the delta to update the > - * global count. > - * > - * Updates: > - * chunk->contig_bits > - * chunk->contig_bits_start > - */ > -static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk) -{ > - int bit_off, bits; > - > - /* clear metadata */ > - chunk->contig_bits = 0; > - > - bit_off = chunk->first_bit; > - bits = 0; > - pcpu_for_each_md_free_region(chunk, bit_off, bits) { > - pcpu_chunk_update(chunk, bit_off, bits); > - } > -} > - > /** > * pcpu_block_update - updates a block given a free area > * @block: block of interest > @@ -753,6 +708,29 @@ static void pcpu_block_update_scan(struct > pcpu_chunk *chunk, int bit_off, > pcpu_block_update(block, s_off, e_off); } > > +/** > + * pcpu_chunk_refresh_hint - updates metadata about a chunk > + * @chunk: chunk of interest > + * > + * Iterates over the metadata blocks to find the largest contig area. > + * It also counts the populated pages and uses the delta to update the > + * global count. > + */ > +static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk) { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > + int bit_off, bits; > + > + /* clear metadata */ > + chunk_md->contig_hint = 0; > + > + bit_off = chunk_md->first_free; > + bits = 0; > + pcpu_for_each_md_free_region(chunk, bit_off, bits) { > + pcpu_block_update(chunk_md, bit_off, bit_off + bits); > + } > +} > + > /** > * pcpu_block_refresh_hint > * @chunk: chunk of interest > @@ -800,6 +778,7 @@ static void pcpu_block_refresh_hint(struct > pcpu_chunk *chunk, int index) static void > pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off, > int bits) > { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > int nr_empty_pages = 0; > struct pcpu_block_md *s_block, *e_block, *block; > int s_index, e_index; /* block indexes of the freed allocation */ > @@ -910,8 +889,9 @@ static void pcpu_block_update_hint_alloc(struct > pcpu_chunk *chunk, int bit_off, > * contig hint is broken. Otherwise, it means a smaller space > * was used and therefore the chunk contig hint is still correct. > */ > - if (pcpu_region_overlap(chunk->contig_bits_start, > - chunk->contig_bits_start + chunk->contig_bits, > + if (pcpu_region_overlap(chunk_md->contig_hint_start, > + chunk_md->contig_hint_start + > + chunk_md->contig_hint, > bit_off, > bit_off + bits)) > pcpu_chunk_refresh_hint(chunk); > @@ -930,9 +910,10 @@ static void pcpu_block_update_hint_alloc(struct > pcpu_chunk *chunk, int bit_off, > * > * A chunk update is triggered if a page becomes free, a block becomes free, > * or the free spans across blocks. This tradeoff is to minimize iterating > - * over the block metadata to update chunk->contig_bits. > chunk->contig_bits > - * may be off by up to a page, but it will never be more than the available > - * space. If the contig hint is contained in one block, it will be accurate. > + * over the block metadata to update chunk_md->contig_hint. > + * chunk_md->contig_hint may be off by up to a page, but it will never > + be more > + * than the available space. If the contig hint is contained in one > + block, it > + * will be accurate. > */ > static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int > bit_off, > int bits) > @@ -1026,8 +1007,9 @@ static void pcpu_block_update_hint_free(struct > pcpu_chunk *chunk, int bit_off, > if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index) > pcpu_chunk_refresh_hint(chunk); > else > - pcpu_chunk_update(chunk, pcpu_block_off_to_off(s_index, start), > - end - start); > + pcpu_block_update(&chunk->chunk_md, > + pcpu_block_off_to_off(s_index, start), > + end); > } > > /** > @@ -1082,6 +1064,7 @@ static bool pcpu_is_populated(struct pcpu_chunk > *chunk, int bit_off, int bits, static int pcpu_find_block_fit(struct pcpu_chunk > *chunk, int alloc_bits, > size_t align, bool pop_only) > { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > int bit_off, bits, next_off; > > /* > @@ -1090,12 +1073,12 @@ static int pcpu_find_block_fit(struct pcpu_chunk > *chunk, int alloc_bits, > * cannot fit in the global hint, there is memory pressure and creating > * a new chunk would happen soon. > */ > - bit_off = ALIGN(chunk->contig_bits_start, align) - > - chunk->contig_bits_start; > - if (bit_off + alloc_bits > chunk->contig_bits) > + bit_off = ALIGN(chunk_md->contig_hint_start, align) - > + chunk_md->contig_hint_start; > + if (bit_off + alloc_bits > chunk_md->contig_hint) > return -1; > > - bit_off = chunk->first_bit; > + bit_off = chunk_md->first_free; > bits = 0; > pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) { > if (!pop_only || pcpu_is_populated(chunk, bit_off, bits, @@ -1190,6 > +1173,7 @@ static unsigned long pcpu_find_zero_area(unsigned long *map, > static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits, > size_t align, int start) > { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > size_t align_mask = (align) ? (align - 1) : 0; > unsigned long area_off = 0, area_bits = 0; > int bit_off, end, oslot; > @@ -1222,8 +1206,8 @@ static int pcpu_alloc_area(struct pcpu_chunk > *chunk, int alloc_bits, > chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE; > > /* update first free bit */ > - if (bit_off == chunk->first_bit) > - chunk->first_bit = find_next_zero_bit( > + if (bit_off == chunk_md->first_free) > + chunk_md->first_free = find_next_zero_bit( > chunk->alloc_map, > pcpu_chunk_map_bits(chunk), > bit_off + alloc_bits); > @@ -1245,6 +1229,7 @@ static int pcpu_alloc_area(struct pcpu_chunk > *chunk, int alloc_bits, > */ > static void pcpu_free_area(struct pcpu_chunk *chunk, int off) { > + struct pcpu_block_md *chunk_md = &chunk->chunk_md; > int bit_off, bits, end, oslot; > > lockdep_assert_held(&pcpu_lock); > @@ -1264,7 +1249,7 @@ static void pcpu_free_area(struct pcpu_chunk > *chunk, int off) > chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE; > > /* update first free bit */ > - chunk->first_bit = min(chunk->first_bit, bit_off); > + chunk_md->first_free = min(chunk_md->first_free, bit_off); > > pcpu_block_update_hint_free(chunk, bit_off, bits); > > @@ -1285,6 +1270,9 @@ static void pcpu_init_md_blocks(struct pcpu_chunk > *chunk) { > struct pcpu_block_md *md_block; > > + /* init the chunk's block */ > + pcpu_init_md_block(&chunk->chunk_md, > pcpu_chunk_map_bits(chunk)); > + > for (md_block = chunk->md_blocks; > md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk); > md_block++) > @@ -1352,7 +1340,6 @@ static struct pcpu_chunk * __init > pcpu_alloc_first_chunk(unsigned long tmp_addr, > chunk->nr_populated = chunk->nr_pages; > chunk->nr_empty_pop_pages = chunk->nr_pages; > > - chunk->contig_bits = map_size / PCPU_MIN_ALLOC_SIZE; > chunk->free_bytes = map_size; > > if (chunk->start_offset) { > @@ -1362,7 +1349,7 @@ static struct pcpu_chunk * __init > pcpu_alloc_first_chunk(unsigned long tmp_addr, > set_bit(0, chunk->bound_map); > set_bit(offset_bits, chunk->bound_map); > > - chunk->first_bit = offset_bits; > + chunk->chunk_md.first_free = offset_bits; > > pcpu_block_update_hint_alloc(chunk, 0, offset_bits); > } > @@ -1415,7 +1402,6 @@ static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t > gfp) > pcpu_init_md_blocks(chunk); > > /* init metadata */ > - chunk->contig_bits = region_bits; > chunk->free_bytes = chunk->nr_pages * PAGE_SIZE; > > return chunk; Reviewed-by: Peng Fan <peng.fan@xxxxxxx> Nitpick, how about name a function __pcpu_md_update, and let pcpu_chunk_update and pcpu_block_update to call __pcpu_md_update. If you prefer, I could submit a patch. Thanks, Peng. > -- > 2.17.1
