On Nov 7, 2022, at 5:21 AM, Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> wrote:
>
> From: Wang Shilong <wshilong@xxxxxxx>
>
> number of threads in pfsck should not exceed flex bg numbers.
> This patch adds the support in libext2fs to calculate
> ext2fs_get_avg_group() which returns an average group
> count which each thread has to scan.
>
> fs->fs_num_threads will be set by the client, in this case e2fsck.
> No. of threads will be passed along with -m option while running e2fsck.
> That will also set fs->fs_num_threads, which will help in controlling
> the amount of memory consumed to maintain in memory data structures (per
> thread) in case of multiple parallel threads (pfsck) to avoid oom.
>
> Signed-off-by: Wang Shilong <wshilong@xxxxxxx>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
> ---
> lib/ext2fs/ext2fs.h | 32 +++++++++++++++++++++++++++++++-
> 1 file changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> index b1505f95..6b4926ce 100644
> --- a/lib/ext2fs/ext2fs.h
> +++ b/lib/ext2fs/ext2fs.h
> @@ -279,10 +279,11 @@ struct struct_ext2_filsys {
> int cluster_ratio_bits;
> __u16 default_bitmap_type;
> __u16 pad;
> + __u32 fs_num_threads;
From later cleanup patch, fs_num_threads should just use "__u16 pad" field.
Otherwise, looks OK.
> /*
> * Reserved for future expansion
> */
> - __u32 reserved[5];
> + __u32 reserved[4];
>
> /*
> * Reserved for the use of the calling application.
> @@ -2231,6 +2232,35 @@ ext2fs_orphan_block_tail(ext2_filsys fs, char *buf)
> sizeof(struct ext4_orphan_block_tail));
> }
>
> +static dgrp_t ext2fs_get_avg_group(ext2_filsys fs)
> +{
> +#ifdef HAVE_PTHREAD
> + dgrp_t average_group;
> + unsigned flexbg_size;
> +
> + if (fs->fs_num_threads <= 1)
> + return fs->group_desc_count;
> +
> + average_group = fs->group_desc_count / fs->fs_num_threads;
> + if (average_group <= 1)
> + return 1;
> +
> + if (ext2fs_has_feature_flex_bg(fs->super)) {
> + int times = 1;
> +
> + flexbg_size = 1 << fs->super->s_log_groups_per_flex;
> + if (average_group % flexbg_size) {
> + times = average_group / flexbg_size;
> + average_group = times * flexbg_size;
> + }
> + }
> +
> + return average_group;
> +#else
> + return fs->group_desc_count;
> +#endif
> +}
> +
> #undef _INLINE_
> #endif
>
> --
> 2.37.3
>
Cheers, Andreas
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