From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Becker Date: Mon, 22 Mar 2010 19:37:41 -0700 Subject: [Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v2. In-Reply-To: <1267091348-26923-1-git-send-email-tristan.ye@oracle.com> References: <1267091348-26923-1-git-send-email-tristan.ye@oracle.com> Message-ID: <20100323023740.GE12279@mail.oracle.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com On Thu, Feb 25, 2010 at 05:49:08PM +0800, Tristan Ye wrote: > =========================================================================== > * Former punching-hole mechanism: > =========================================================================== > > I waited 1 hour for its completion, unfortunately it's still ongoing. > > =========================================================================== > * Patched punching-hode mechanism: > =========================================================================== > > real 0m2.518s > user 0m0.000s > sys 0m2.445s > > That means we've gained up to 1000 times improvement on performance in this > case, whee! It's fairly cool. and it looks like that performance gain will > be raising when extent records grow. Love the numbers, obviously. > The patch was based on my former 2 patches, which were about truncating > codes optimization and fixup to handle CoW on punching hole. I've already reviewed these. I'm waiting on Mark's ack for them to go to ocfs2.git. > - cpos = trunc_start; > - while (trunc_len) { > - ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, > - &alloc_size, &flags); > - if (ret) { > - mlog_errno(ret); > - goto out; > - } > + path = ocfs2_new_path_from_et(&et); > + if (!path) { > + ret = -ENOMEM; > + mlog_errno(ret); > + goto out; > + } > + > +start: > + if (trunc_end == 0) { > + ret = 0; > + goto out; > + } NO! Don't do loops via goto. Just Don't. There are some convoluted functions that end up being cleaner with gotos, but they are *convoluted*. This is a simple loop. Keep it that way. In fact, this all really wants to be a helper function: while (trunc_end > 0) { do_one_hunk(); ocfs2_reinit_path(path, 1); } Actually, looking at the rest of the code, I see a couple helpers. If you wrap trunc_start, trunc_len, etc in a structure, you can pass it through. > > - if (alloc_size > trunc_len) > - alloc_size = trunc_len; > + /* > + * Unlike truncating codes, here we want to find a path which contains > + * (trunc_end - 1) cpos, and trunc_end will be decreased after each > + * removal of a record range. > + * > + * Why didn't use trunc_end to search the path? > + * The reason is simple, think about the situation when we cross the > + * extent block, we need to find the adjacent block by decreasing one > + * cluster, otherwise, it will run into loop. > + */ > + ret = ocfs2_find_path(INODE_CACHE(inode), path, cluster_within_list); > + if (ret) { > + mlog_errno(ret); > + goto out; > + } > > - /* Only do work for non-holes */ > - if (phys_cpos != 0) { > - ret = ocfs2_remove_btree_range(inode, &et, cpos, > - phys_cpos, alloc_size, > - &dealloc, refcount_loc, > - flags); > - if (ret) { > - mlog_errno(ret); > - goto out; > - } > + el = path_leaf_el(path); > + > + for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) { > + rec = &el->l_recs[i]; > + /* > + * Find the rightmost record which contains 'trunc_end' cpos, > + * and we just simply jump to previous record if the trunc_end > + * is the start of a record. > + */ > + if (le32_to_cpu(rec->e_cpos) < trunc_end) { > + /* > + * Skip a hole. > + */ > + if ((le32_to_cpu(rec->e_cpos) + > + ocfs2_rec_clusters(el, rec)) < trunc_end) > + trunc_end = le32_to_cpu(rec->e_cpos) + > + ocfs2_rec_clusters(el, rec); > + break; > } > > - cpos += alloc_size; > - trunc_len -= alloc_size; > + if (le32_to_cpu(rec->e_cpos) == trunc_end) { > + i--; > + break; > + } > + } > + > + rec = &el->l_recs[i]; This is the first helper. It finds the rec. > + flags = rec->e_flags; > + range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec); > + > + /* > + * Similar with the truncating codes, we also handle the > + * following three cases in order: > + * > + * - remove the entire record > + * - remove a partial record > + * - no record needs to be removed > + */ > + if (le32_to_cpu(rec->e_cpos) >= trunc_start) { > + trunc_cpos = le32_to_cpu(rec->e_cpos); > + trunc_len = trunc_end - le32_to_cpu(rec->e_cpos); > + blkno = le64_to_cpu(rec->e_blkno); > + trunc_end = le32_to_cpu(rec->e_cpos); > + } else if (range > trunc_start) { > + trunc_cpos = trunc_start; > + trunc_len = range - trunc_start; > + coff = trunc_start - le32_to_cpu(rec->e_cpos); > + blkno = le64_to_cpu(rec->e_blkno) + > + ocfs2_clusters_to_blocks(inode->i_sb, coff); > + trunc_end = trunc_start; > + } else { > + /* > + * It may have two following possibilities: > + * > + * - last record has been removed > + * - trunc_start was within a hole > + * > + * both two cases mean the completion of hole punching. > + */ > + ret = 0; > + goto out; > } > > + phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno); This is the second helper. It computes the actual results from the found record. > + ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos, > + phys_cpos, trunc_len, &dealloc, > + refcount_loc, flags); > + if (ret < 0) { > + mlog_errno(ret); > + goto out; > + } > + > + if (trunc_end > 0) > + cluster_within_list = trunc_end - 1; This is the third helper. It does the actual punch. Joel -- "There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle." - Albert Einstein Joel Becker Principal Software Developer Oracle E-mail: joel.becker at oracle.com Phone: (650) 506-8127