On Feb 9, 2021, at 1:28 PM, Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx> wrote: > > This patch adds a new file "mb_structs_summary" which allows us to see the > summary of the new allocator structures added in this series. Hmm, it is hard to visualize what these files will look like, could you please include an example output in the commit message? It looks like they will no longer have one line per group, which is good, but maybe one line per order? If at all possible, it makes sense to have well-formatted output that follows YAML formatting (https://yaml-online-parser.appspot.com/ can verify this) so that it can be easily parsed (both as YAML and via awk or other text processing tools). That doesn't mean you need to embed a YAML parser, just a few well-placed ':' and spaces... Unfortunately, files like "mb_groups" were created before that wisdom was learned, and are a bit of a nightmare to parse today. A few comments inline... > Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx> > > +static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v) > +{ > + Extra blank line here can be removed > + if (position >= MB_NUM_ORDERS(sb)) { > + seq_puts(seq, "Tree\n"); Prefer not to use capitalized words. This should have a ':' like "tree:", but this still leaves the question "what is the tree for?" so using "fragment_size_tree:" or similar would be better. > + n = rb_first(&sbi->s_mb_avg_fragment_size_root); > + if (!n) { > + seq_puts(seq, "<Empty>\n"); I'm guessing this won't happen very often, but it might be easier if it kept the same output format, so "min: 0, max: 0, num_nodes: 0", or just initialize those values and then skip the intermediate processing below before printing out the summary line (better because there is only one place that is formatting the output, so it will be consistent)? > + return 0; > + } > + grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb); > + min = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0; > + count = 1; > + while (rb_next(n)) { > + count++; > + n = rb_next(n); > + } > + grp = rb_entry(n, struct ext4_group_info, bb_avg_fragment_size_rb); > + max = grp->bb_fragments ? grp->bb_free / grp->bb_fragments : 0; > + > + seq_printf(seq, "Min: %d, Max: %d, Num Nodes: %d\n", These should be "%u" and not "%d"? I'd assume none will ever be negative. Prefer not to have spaces within keys, so that it is possible to use e.g. 'awk /field:/ { print $2 }' to extract a value. "num_nodes:" or "tree_nodes: is better. To be a subset of "tree:" they should be indented with 4 spaces or a tab: fragment_size_tree: tree_min: nnn tree_max: mmm tree_nodes: ooo > + if (position == 0) > + seq_puts(seq, "Largest Free Order Lists:\n"); Similarly, avoiding spaces in the key makes this easier to parse, like "max_free_order_lists:" or similar. > + seq_printf(seq, "Order %ld list: ", position); Here, " list_order_%u: %u groups\n" would be more clear, and can be printed in a single call instead of being split up. Cheers, Andreas
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