On Wed, 2017-04-05 at 15:10 +0800, Huang, Ying wrote: > To solve the issue, the per-CPU buffer is sorted according to the > swap > device before freeing the swap entries. Test shows that the time > spent by swapcache_free_entries() could be reduced after the patch.
That makes a lot of sense.
> @@ -1075,6 +1083,8 @@ void swapcache_free_entries(swp_entry_t
> *entries, int n)
>
> prev = NULL;
> p = NULL;
> + if (nr_swapfiles > 1)
> + sort(entries, n, sizeof(entries[0]), swp_entry_cmp,
> NULL);
But it really wants a comment in the code, so people
reading the code a few years from now can see why
we are sorting things we are about to free.
Maybe something like:
/* Sort swap entries by swap device, so each lock is only taken
once. */
> for (i = 0; i < n; ++i) {
> p = swap_info_get_cont(entries[i], prev);
> if (p)
--
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