> -----Original Message----- > From: Dennis Zhou [mailto:dennis@xxxxxxxxxx] > Sent: 2019年3月4日 4:22 > To: Peng Fan <peng.fan@xxxxxxx> > Cc: Dennis Zhou <dennis@xxxxxxxxxx>; Tejun Heo <tj@xxxxxxxxxx>; Christoph > Lameter <cl@xxxxxxxxx>; Vlad Buslov <vladbu@xxxxxxxxxxxx>; > kernel-team@xxxxxx; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 11/12] percpu: convert chunk hints to be based on > pcpu_block_md > > On Sun, Mar 03, 2019 at 08:18:49AM +0000, Peng Fan wrote: > > > > > > > -----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. > > > > I don't have a preference. But I do not really want to have 2 functions that just > wrap the same function. I think overall it'll make sense to rename it, but I > haven't thought about what to rename it to as it'll probably be influence by > the possible direction that percpu ends up going. ok, then I just leave it up to you. Thanks, Peng. > > Thanks, > Dennis
