Re: + mm-swapc-reduce-lock-contention-in-lru_cache_add.patch added to -mm tree

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Hi Andrew,

Would you like to drop this patch, since a better inplace sorting patchset
in cooking.

Thanks a lot!
Alex


在 2020/11/24 上午9:12, akpm@xxxxxxxxxxxxxxxxxxxx 写道:
> The patch titled
>      Subject: mm/swap.c: reduce lock contention in lru_cache_add
> has been added to the -mm tree.  Its filename is
>      mm-swapc-reduce-lock-contention-in-lru_cache_add.patch
> 
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/mm-swapc-reduce-lock-contention-in-lru_cache_add.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/mm-swapc-reduce-lock-contention-in-lru_cache_add.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
> Subject: mm/swap.c: reduce lock contention in lru_cache_add
> 
> The current relock logic will change lru_lock when it finds a new lruvec,
> so if 2 memcgs are reading a file or allocating pages at same time, they
> could hold the lru_lock alternately, and wait for each other for fairness
> attribute of ticket spin lock.
> 
> This patch will sort all lru_locks and only hold them once in the above
> scenario.  That could reduce fairness waiting for lock reacquision. 
> vm-scalability/case-lru-file-readtwice gets a ~5% performance gain on my
> 2P*20core*HT machine.
> 
> Testing when all or most of the pages belong to the same lruvec show no
> regression - most time is spent on lru_lock for lru sensitive cases.
> 
> Link: https://lkml.kernel.org/r/1605860847-47445-1-git-send-email-alex.shi@xxxxxxxxxxxxxxxxx
> Suggested-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
> Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
> Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> 
>  mm/swap.c |   57 ++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 49 insertions(+), 8 deletions(-)
> 
> --- a/mm/swap.c~mm-swapc-reduce-lock-contention-in-lru_cache_add
> +++ a/mm/swap.c
> @@ -1009,24 +1009,65 @@ static void __pagevec_lru_add_fn(struct
>  	trace_mm_lru_insertion(page, lru);
>  }
>  
> +struct lruvecs {
> +	struct list_head lists[PAGEVEC_SIZE];
> +	struct lruvec *vecs[PAGEVEC_SIZE];
> +};
> +
> +/* Sort pvec pages on their lruvec */
> +int sort_page_lruvec(struct lruvecs *lruvecs, struct pagevec *pvec)
> +{
> +	int i, j, nr_lruvec;
> +	struct page *page;
> +	struct lruvec *lruvec = NULL;
> +
> +	lruvecs->vecs[0] = NULL;
> +	for (i = nr_lruvec = 0; i < pagevec_count(pvec); i++) {
> +		page = pvec->pages[i];
> +		lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> +
> +		/* Try to find a same lruvec */
> +		for (j = 0; j <= nr_lruvec; j++)
> +			if (lruvec == lruvecs->vecs[j])
> +				break;
> +
> +		/* A new lruvec */
> +		if (j > nr_lruvec) {
> +			INIT_LIST_HEAD(&lruvecs->lists[nr_lruvec]);
> +			lruvecs->vecs[nr_lruvec] = lruvec;
> +			j = nr_lruvec++;
> +			lruvecs->vecs[nr_lruvec] = 0;
> +		}
> +
> +		list_add_tail(&page->lru, &lruvecs->lists[j]);
> +	}
> +
> +	return nr_lruvec;
> +}
> +
>  /*
>   * Add the passed pages to the LRU, then drop the caller's refcount
>   * on them.  Reinitialises the caller's pagevec.
>   */
>  void __pagevec_lru_add(struct pagevec *pvec)
>  {
> -	int i;
> -	struct lruvec *lruvec = NULL;
> +	int i, nr_lruvec;
>  	unsigned long flags = 0;
> +	struct page *page;
> +	struct lruvecs lruvecs;
>  
> -	for (i = 0; i < pagevec_count(pvec); i++) {
> -		struct page *page = pvec->pages[i];
> +	nr_lruvec = sort_page_lruvec(&lruvecs, pvec);
>  
> -		lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
> -		__pagevec_lru_add_fn(page, lruvec);
> +	for (i = 0; i < nr_lruvec; i++) {
> +		spin_lock_irqsave(&lruvecs.vecs[i]->lru_lock, flags);
> +		while (!list_empty(&lruvecs.lists[i])) {
> +			page = lru_to_page(&lruvecs.lists[i]);
> +			list_del(&page->lru);
> +			__pagevec_lru_add_fn(page, lruvecs.vecs[i]);
> +		}
> +		spin_unlock_irqrestore(&lruvecs.vecs[i]->lru_lock, flags);
>  	}
> -	if (lruvec)
> -		unlock_page_lruvec_irqrestore(lruvec, flags);
> +
>  	release_pages(pvec->pages, pvec->nr);
>  	pagevec_reinit(pvec);
>  }
> _
> 
> Patches currently in -mm which might be from alex.shi@xxxxxxxxxxxxxxxxx are
> 
> mm-filemap-add-static-for-function-__add_to_page_cache_locked.patch
> fs-ntfs-remove-unused-varibles.patch
> fs-ntfs-remove-unused-varible-attr_len.patch
> mm-truncate-add-parameter-explanation-for-invalidate_mapping_pagevec.patch
> mm-memcg-update-page-struct-member-in-comments.patch
> mm-thp-move-lru_add_page_tail-func-to-huge_memoryc.patch
> mm-thp-use-head-for-head-page-in-lru_add_page_tail.patch
> mm-thp-simplify-lru_add_page_tail.patch
> mm-thp-narrow-lru-locking.patch
> mm-vmscan-remove-unnecessary-lruvec-adding.patch
> mm-rmap-stop-store-reordering-issue-on-page-mapping.patch
> mm-rmap-stop-store-reordering-issue-on-page-mapping-fix.patch
> mm-memcg-add-debug-checking-in-lock_page_memcg.patch
> mm-swapc-fold-vm-event-pgrotated-into-pagevec_move_tail_fn.patch
> mm-lru-move-lock-into-lru_note_cost.patch
> mm-vmscan-remove-lruvec-reget-in-move_pages_to_lru.patch
> mm-mlock-remove-lru_lock-on-testclearpagemlocked.patch
> mm-mlock-remove-__munlock_isolate_lru_page.patch
> mm-lru-introduce-testclearpagelru.patch
> mm-compaction-do-page-isolation-first-in-compaction.patch
> mm-swapc-serialize-memcg-changes-in-pagevec_lru_move_fn.patch
> mm-lru-replace-pgdat-lru_lock-with-lruvec-lock.patch
> mm-lru-replace-pgdat-lru_lock-with-lruvec-lock-fix.patch
> mm-lru-replace-pgdat-lru_lock-with-lruvec-lock-fix-2.patch
> mm-lru-introduce-the-relock_page_lruvec-function-fix.patch
> mm-memcg-remove-incorrect-comments.patch
> mm-mapping_dirty_helpers-enhance-the-kernel-doc-markups.patch
> mm-add-colon-to-fix-kernel-doc-markups-error-for-check_pte.patch
> mm-vmalloc-add-align-parameter-explanation-for-pvm_determine_end_from_reverse.patch
> docs-vm-remove-unused-3-items-explanation-for-proc-vmstat.patch
> khugepaged-add-couples-parameter-explanation-for-kernel-doc-markup.patch
> gcov-fix-kernel-doc-markup-issue.patch
> mm-swapc-reduce-lock-contention-in-lru_cache_add.patch
> mm-memcg-bail-early-from-swap-accounting-if-memcg-disabled.patch
> mm-memcg-warning-on-memcg-after-readahead-page-charged.patch
> mm-memcontrol-rewrite-mem_cgroup_page_lruvec-fix.patch
> 



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