On Wed, 26 Jun 2019 11:04:29 -0700 semenzato@xxxxxxxxxxxx wrote:
> From: Luigi Semenzato <semenzato@xxxxxxxxxxxx>
>
> Report separate components (anon, file, and shmem)
> for PSS in smaps_rollup.
>
> This helps understand and tune the memory manager behavior
> in consumer devices, particularly mobile devices. Many of
> them (e.g. chromebooks and Android-based devices) use zram
> for anon memory, and perform disk reads for discarded file
> pages. The difference in latency is large (e.g. reading
> a single page from SSD is 30 times slower than decompressing
> a zram page on one popular device), thus it is useful to know
> how much of the PSS is anon vs. file.
>
> This patch also removes a small code duplication in smaps_account,
> which would have gotten worse otherwise.
>
> Also added missing entry for smaps_rollup in
> Documentation/filesystems/proc.txt.
>
> ...
>
> -static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss)
> +static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
> + bool rollup_mode)
> {
> SEQ_PUT_DEC("Rss: ", mss->resident);
> SEQ_PUT_DEC(" kB\nPss: ", mss->pss >> PSS_SHIFT);
> + if (rollup_mode) {
> + /*
> + * These are meaningful only for smaps_rollup, otherwise two of
> + * them are zero, and the other one is the same as Pss.
> + */
> + SEQ_PUT_DEC(" kB\nPss_Anon: ",
> + mss->pss_anon >> PSS_SHIFT);
> + SEQ_PUT_DEC(" kB\nPss_File: ",
> + mss->pss_file >> PSS_SHIFT);
> + SEQ_PUT_DEC(" kB\nPss_Shmem: ",
> + mss->pss_shmem >> PSS_SHIFT);
> + }
Documentation/filesystems/proc.txt is rather incomplete. It documents
/proc/PID/smaps (seems to be out of date) but doesn't describe the
fields in smaps_rollup.
Please update Documentation/ABI/testing/procfs-smaps_rollup and please
check that it's up-to-date while you're in there.
