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Date: Thu, 17 Mar 2011 15:19:52 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Lukas Czerner <lczerner@...hat.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, sandeen@...hat.com
Subject: Re: [PATCH 4/4] Add macro to enable collecting bitmap statistics
On 2011-03-17, at 12:50 PM, Lukas Czerner wrote:
> This commit adds a new preprocessor macro BMAP_STATS, which can be
> defined in ext2fs.h. Setting this macro, the code for statistic
> collection of bitmap handling is enabled and once the bitmap shall be
> freed collected information is printed to the stderr.
>
> This feature is especially useful for better understanding how e2fsprogs
> tools (mainly e2fsck) treats bitmaps and what bitmap backend can be most
> suitable for particular bitmap. Backend itself (if implemented) can
> provide statistics of its own as well.
>
> I was thinking about enabling this feature simply by setting program
> parameter, however collecting of the statistic, even conditional, means
> unnecessary overhead. And since information provided is usually relevant
> only for e2fsprogs developers, I decided to use preprocessor macro
> instead.
Being able to turn this on/off at runtime without needing to recompile is pretty important. It is fine to allow it to be #ifdef out entirely, but if it is enabled it is good to be able to turn it on/off via the command-line.
> @@ -245,8 +260,8 @@ errcode_t ext2fs_alloc_generic_bmap(ext2_filsys fs, errcode_t magic,
>
> retval = bitmap->bitmap_ops->new_bmap(fs, bitmap);
> if (retval) {
> - ext2fs_free_mem(&bitmap);
> ext2fs_free_mem(&bitmap->description);
> + ext2fs_free_mem(&bitmap);
This looks like a bug in the upstream code that should be submitted separately. However, I don't see this bug in my tree (it is correctly ordered already), and I don't see it being introduced by your patches... It again makes me wonder which branch these patches are against.
> + fprintf(stderr, "\n[+] %s bitmap\n", bmap_defs[stats->type].descr);
> + fprintf(stderr, "=================================================\n");
> + fprintf(stderr, "%16d type\n%16d backend\n",
> + stats->type, bmap_defs[stats->type].backend);
> + fprintf(stderr, "%16d bits long\n",
> + bitmap->real_end - bitmap->start);
> + fprintf(stderr, "%16lu copy_bmap\n%16lu resize_bmap\n",
> + stats->copy_count, stats->resize_count);
> + fprintf(stderr, "%16lu mark bmap\n%16lu unmark_bmap\n",
> + stats->mark_count, stats->unmark_count);
> + fprintf(stderr, "%16lu test_bmap\n%16lu mark_bmap_extent\n",
> + stats->test_count, stats->mark_ext_count);
> + fprintf(stderr, "%16lu unmark_bmap_extent\n"
> + "%16lu test_clear_bmap_extent\n",
> + stats->unmark_ext_count, stats->test_ext_count);
> + fprintf(stderr, "%16lu set_bmap_range\n%16lu set_bmap_range\n",
> + stats->set_range_count, stats->get_range_count);
> + fprintf(stderr, "%16lu clear_bmap\n%16lu contiguous bit test (%.2f%)\n",
> + stats->clear_count, stats->test_seq, test_seq_perc);
> + fprintf(stderr, "%16lu contiguous bit mark (%.2f%)\n"
> + "%16lu bits tested backwards (%.2f%)\n",
> + stats->mark_seq, mark_seq_perc,
> + stats->test_back, test_back_perc);
> + fprintf(stderr, "%16lu bits marked backwards (%.2f%)\n"
> + "%16.2f seconds in use\n",
> + stats->mark_back, mark_back_perc, inuse);
> +}
This should include the amount of memory used by the bitmap, which is one of the most important stats for this code.
> +#endif
> +
> void ext2fs_free_generic_bmap(ext2fs_generic_bitmap bmap)
> {
> if (!bmap)
> @@ -267,6 +338,16 @@ void ext2fs_free_generic_bmap(ext2fs_generic_bitmap bmap)
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return;
>
> +#ifdef BMAP_STATS
> + if (gettimeofday(&bmap->stats.destroyed,
> + (struct timezone *) NULL) == -1) {
> + perror("gettimeofday");
> + return;
> + }
> + ext2fs_print_bmap_statistics(bmap);
> + bmap->bitmap_ops->print_stats(bmap);
> +#endif
> +
> bmap->bitmap_ops->free_bmap(bmap);
>
> if (bmap->description) {
> @@ -300,6 +381,17 @@ errcode_t ext2fs_copy_generic_bmap(ext2fs_generic_bitmap src,
> return retval;
> memset(new_bmap, 0, sizeof(struct ext2fs_struct_generic_bitmap));
>
> +
> +#ifdef BMAP_STATS
> + src->stats.copy_count++;
> + if (gettimeofday(&new_bmap->stats.created,
> + (struct timezone *) NULL) == -1) {
> + perror("gettimeofday");
> + return 1;
> + }
> + new_bmap->stats.type = src->stats.type;
> +#endif
> +
> /* Copy all the high-level parts over */
> new_bmap->magic = src->magic;
> new_bmap->fs = src->fs;
> @@ -346,6 +438,8 @@ errcode_t ext2fs_resize_generic_bmap(ext2fs_generic_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return EINVAL;
>
> + INC_STAT(bmap, resize_count);
> +
> return bmap->bitmap_ops->resize_bmap(bmap, new_end, new_real_end);
> }
>
> @@ -432,6 +526,15 @@ int ext2fs_mark_generic_bmap(ext2fs_generic_bitmap bitmap,
> if (!EXT2FS_IS_64_BITMAP(bitmap))
> return 0;
>
> +#ifdef BMAP_STATS
> + if (arg == bitmap->stats.last_marked + 1)
> + bitmap->stats.mark_seq++;
> + if (arg < bitmap->stats.last_marked)
> + bitmap->stats.mark_back++;
> + bitmap->stats.last_marked = arg;
> + bitmap->stats.mark_count++;
> +#endif
> +
> if ((arg < bitmap->start) || (arg > bitmap->end)) {
> warn_bitmap(bitmap, EXT2FS_MARK_ERROR, arg);
> return 0;
> @@ -458,6 +561,8 @@ int ext2fs_unmark_generic_bmap(ext2fs_generic_bitmap bitmap,
> if (!EXT2FS_IS_64_BITMAP(bitmap))
> return 0;
>
> + INC_STAT(bitmap, unmark_count);
> +
> if ((arg < bitmap->start) || (arg > bitmap->end)) {
> warn_bitmap(bitmap, EXT2FS_UNMARK_ERROR, arg);
> return 0;
> @@ -484,6 +589,15 @@ int ext2fs_test_generic_bmap(ext2fs_generic_bitmap bitmap,
> if (!EXT2FS_IS_64_BITMAP(bitmap))
> return 0;
>
> +#ifdef BMAP_STATS
> + bitmap->stats.test_count++;
> + if (arg == bitmap->stats.last_tested + 1)
> + bitmap->stats.test_seq++;
> + if (arg < bitmap->stats.last_tested)
> + bitmap->stats.test_back++;
> + bitmap->stats.last_tested = arg;
> +#endif
> +
> if ((arg < bitmap->start) || (arg > bitmap->end)) {
> warn_bitmap(bitmap, EXT2FS_TEST_ERROR, arg);
> return 0;
> @@ -512,6 +626,8 @@ errcode_t ext2fs_set_generic_bmap_range(ext2fs_generic_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return EINVAL;
>
> + INC_STAT(bmap, set_range_count);
> +
> return bmap->bitmap_ops->set_bmap_range(bmap, start, num, in);
> }
>
> @@ -535,6 +651,8 @@ errcode_t ext2fs_get_generic_bmap_range(ext2fs_generic_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return EINVAL;
>
> + INC_STAT(bmap, get_range_count);
> +
> return bmap->bitmap_ops->get_bmap_range(bmap, start, num, out);
> }
>
> @@ -606,6 +724,8 @@ int ext2fs_test_block_bitmap_range2(ext2fs_block_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return EINVAL;
>
> + INC_STAT(bmap, test_ext_count);
> +
> return bmap->bitmap_ops->test_clear_bmap_extent(bmap, block, num);
> }
>
> @@ -628,6 +748,8 @@ void ext2fs_mark_block_bitmap_range2(ext2fs_block_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return;
>
> + INC_STAT(bmap, mark_ext_count);
> +
> if ((block < bmap->start) || (block+num-1 > bmap->end)) {
> ext2fs_warn_bitmap(EXT2_ET_BAD_BLOCK_MARK, block,
> bmap->description);
> @@ -656,6 +778,8 @@ void ext2fs_unmark_block_bitmap_range2(ext2fs_block_bitmap bmap,
> if (!EXT2FS_IS_64_BITMAP(bmap))
> return;
>
> + INC_STAT(bmap, unmark_ext_count);
> +
> if ((block < bmap->start) || (block+num-1 > bmap->end)) {
> ext2fs_warn_bitmap(EXT2_ET_BAD_BLOCK_UNMARK, block,
> bmap->description);
> --
> 1.7.4
>
> --
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Cheers, Andreas
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