Hi Weiwen, On Fri, Jan 01, 2021 at 09:50:24AM +0000, 胡 玮文 wrote: > Hi all, > > This is my first time sending patches by email. If something is not properly > done, please point it out. > > I have a question for now: How am I supposed to submit patches to erofs-utils > now? Some E-mail address listed in AUTHORS and README seems no longer valid > (email to [email protected]<mailto:[email protected]> was rejected). > Is it enough to post the patches to this mailing list? I added all addresses > in README, but I got a message said my email is rejected. I’m not sure who > actually received my email.
My email has been changed, I might need to update my email address to [email protected]... Thanks for point out! Yeah, that could cause bottleneck when files increased (Android only have < 10000 files), so it needs to be improve. I will look into your patch later (working on another things now...) Hope Guifu or other folks could also help reviewing that... Thanks, Gao Xiang > > 发件人: 胡 玮文<mailto:[email protected]> > 发送时间: 2021年1月1日 17:16 > 收件人: Li Guifu<mailto:[email protected]>; Miao > Xie<mailto:[email protected]>; Fang Wei<mailto:[email protected]> > 抄送: Gao Xiang<mailto:[email protected]>; Chao > Yu<mailto:[email protected]>; > [email protected]<mailto:[email protected]>; > 胡玮文<mailto:[email protected]> > 主题: [PATCH 1/2] erofs-utils: optimize mkfs to O(N), N = #files > > When using EROFS to pack our dataset which consists of millions of > files, mkfs.erofs is very slow compared with mksquashfs. > > The bottleneck is `erofs_balloc` and `erofs_mapbh` function, which > iterate over all previously allocated buffer blocks, making the > complexity of the algrithm O(N^2) where N is the number of files. > > With this patch: > > * global `last_mapped_block` is mantained to avoid full scan in > `erofs_mapbh` function. > > * global `non_full_buffer_blocks` mantains a list of buffer block for > each type and each possible remaining bytes in the block. Then it is > used to identify the most suitable blocks in future `erofs_balloc`, > avoiding full scan. > > Some new data structure is allocated in this patch, more RAM usage is > expected, but not much. When I test it with ImageNet dataset (1.33M > files), 7GiB RAM is consumed, and it takes about 4 hours. Most time is > spent on IO. > > Signed-off-by: Hu Weiwen <[email protected]> > --- > lib/cache.c | 102 +++++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 89 insertions(+), 13 deletions(-) > > diff --git a/lib/cache.c b/lib/cache.c > index 0d5c4a5..3412a0b 100644 > --- a/lib/cache.c > +++ b/lib/cache.c > @@ -18,6 +18,18 @@ static struct erofs_buffer_block blkh = { > }; > static erofs_blk_t tail_blkaddr; > > +/** > + * Some buffers are not full, we can reuse it to store more data > + * 2 for DATA, META > + * EROFS_BLKSIZ for each possible remaining bytes in the last block > + **/ > +static struct erofs_buffer_block_record { > + struct list_head list; > + struct erofs_buffer_block *bb; > +} non_full_buffer_blocks[2][EROFS_BLKSIZ]; > + > +static struct erofs_buffer_block *last_mapped_block = &blkh; > + > static bool erofs_bh_flush_drop_directly(struct erofs_buffer_head *bh) > { > return erofs_bh_flush_generic_end(bh); > @@ -62,6 +74,12 @@ struct erofs_bhops erofs_buf_write_bhops = { > /* return buffer_head of erofs super block (with size 0) */ > struct erofs_buffer_head *erofs_buffer_init(void) > { > + for (int i = 0; i < 2; i++) { > + for (int j = 0; j < EROFS_BLKSIZ; j++) { > + init_list_head(&non_full_buffer_blocks[i][j].list); > + } > + } > + > struct erofs_buffer_head *bh = erofs_balloc(META, 0, 0, 0); > > if (IS_ERR(bh)) > @@ -131,7 +149,8 @@ struct erofs_buffer_head *erofs_balloc(int type, > erofs_off_t size, > { > struct erofs_buffer_block *cur, *bb; > struct erofs_buffer_head *bh; > - unsigned int alignsize, used0, usedmax; > + unsigned int alignsize, used0, usedmax, total_size; > + struct erofs_buffer_block_record * reusing = NULL; > > int ret = get_alignsize(type, &type); > > @@ -143,7 +162,38 @@ struct erofs_buffer_head *erofs_balloc(int type, > erofs_off_t size, > usedmax = 0; > bb = NULL; > > - list_for_each_entry(cur, &blkh.list, list) { > + erofs_dbg("balloc size=%lu alignsize=%u used0=%u", size, alignsize, > used0); > + if (used0 == 0 || alignsize == EROFS_BLKSIZ) { > + goto alloc; > + } > + total_size = size + required_ext + inline_ext; > + if (total_size < EROFS_BLKSIZ) { > + // Try find a most fit block. > + DBG_BUGON(type < 0 || type > 1); > + struct erofs_buffer_block_record *non_fulls = > non_full_buffer_blocks[type]; > + for (struct erofs_buffer_block_record *r = non_fulls + > round_up(total_size, alignsize); > + r < non_fulls + EROFS_BLKSIZ; r++) { > + if (!list_empty(&r->list)) { > + struct erofs_buffer_block_record > *reuse_candidate = > + list_first_entry(&r->list, > struct erofs_buffer_block_record, list); > + ret = __erofs_battach(reuse_candidate->bb, > NULL, size, alignsize, > + required_ext + inline_ext, > true); > + if (ret >= 0) { > + reusing = reuse_candidate; > + bb = reuse_candidate->bb; > + usedmax = (ret + required_ext) % > EROFS_BLKSIZ + inline_ext; > + } > + break; > + } > + } > + } > + > + /* Try reuse last ones, which are not mapped and can be extended */ > + cur = last_mapped_block; > + if (cur == &blkh) { > + cur = list_next_entry(cur, list); > + } > + for (; cur != &blkh; cur = list_next_entry(cur, list)) { > unsigned int used_before, used; > > used_before = cur->buffers.off % EROFS_BLKSIZ; > @@ -175,22 +225,32 @@ struct erofs_buffer_head *erofs_balloc(int type, > erofs_off_t size, > continue; > > if (usedmax < used) { > + reusing = NULL; > bb = cur; > usedmax = used; > } > } > > if (bb) { > + erofs_dbg("reusing buffer. usedmax=%u", usedmax); > bh = malloc(sizeof(struct erofs_buffer_head)); > if (!bh) > return ERR_PTR(-ENOMEM); > + if (reusing) { > + list_del(&reusing->list); > + free(reusing); > + } > goto found; > } > > +alloc: > /* allocate a new buffer block */ > - if (used0 > EROFS_BLKSIZ) > + if (used0 > EROFS_BLKSIZ) { > + erofs_dbg("used0 > EROFS_BLKSIZ"); > return ERR_PTR(-ENOSPC); > + } > > + erofs_dbg("new buffer block"); > bb = malloc(sizeof(struct erofs_buffer_block)); > if (!bb) > return ERR_PTR(-ENOMEM); > @@ -211,6 +271,16 @@ found: > required_ext + inline_ext, false); > if (ret < 0) > return ERR_PTR(ret); > + if (ret != 0) { > + /* This buffer is not full yet, we may reuse it */ > + reusing = malloc(sizeof(struct erofs_buffer_block_record)); > + if (!reusing) { > + return ERR_PTR(-ENOMEM); > + } > + reusing->bb = bb; > + list_add_tail(&reusing->list, > + &non_full_buffer_blocks[type][EROFS_BLKSIZ - > ret - inline_ext].list); > + } > return bh; > } > > @@ -247,8 +317,10 @@ static erofs_blk_t __erofs_mapbh(struct > erofs_buffer_block *bb) > { > erofs_blk_t blkaddr; > > - if (bb->blkaddr == NULL_ADDR) > + if (bb->blkaddr == NULL_ADDR) { > bb->blkaddr = tail_blkaddr; > + last_mapped_block = bb; > + } > > blkaddr = bb->blkaddr + BLK_ROUND_UP(bb->buffers.off); > if (blkaddr > tail_blkaddr) > @@ -259,15 +331,16 @@ static erofs_blk_t __erofs_mapbh(struct > erofs_buffer_block *bb) > > erofs_blk_t erofs_mapbh(struct erofs_buffer_block *bb, bool end) > { > - struct erofs_buffer_block *t, *nt; > - > - if (!bb || bb->blkaddr == NULL_ADDR) { > - list_for_each_entry_safe(t, nt, &blkh.list, list) { > - if (!end && (t == bb || nt == &blkh)) > - break; > - (void)__erofs_mapbh(t); > - if (end && t == bb) > - break; > + DBG_BUGON(!end); > + struct erofs_buffer_block *t = last_mapped_block; > + while (1) { > + t = list_next_entry(t, list); > + if (t == &blkh) { > + break; > + } > + (void)__erofs_mapbh(t); > + if (t == bb) { > + break; > } > } > return tail_blkaddr; > @@ -334,6 +407,9 @@ void erofs_bdrop(struct erofs_buffer_head *bh, bool > tryrevoke) > if (!list_empty(&bb->buffers.list)) > return; > > + if (bb == last_mapped_block) { > + last_mapped_block = list_prev_entry(bb, list); > + } > list_del(&bb->list); > free(bb); > > -- > 2.30.0 >
