From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>,
Chuck Lever <chuck.lever@oracle.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-Net <netdev@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>,
Linux-NFS <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH 7/7] net: page_pool: use alloc_pages_bulk in refill code path
Date: Fri, 12 Mar 2021 22:05:45 +0200 [thread overview]
Message-ID: <YEvJmVrnTzKT1XAY@apalos.home> (raw)
In-Reply-To: <CAKgT0UebK=mMwDV+UH8CqBRt0E0Koc7EB42kwgf0hYHDT_2OfQ@mail.gmail.com>
[...]
> 6. return last_page
>
> > + /* Remaining pages store in alloc.cache */
> > + list_for_each_entry_safe(page, next, &page_list, lru) {
> > + list_del(&page->lru);
> > + if ((pp_flags & PP_FLAG_DMA_MAP) &&
> > + unlikely(!page_pool_dma_map(pool, page))) {
> > + put_page(page);
> > + continue;
> > + }
>
> So if you added a last_page pointer what you could do is check for it
> here and assign it to the alloc cache. If last_page is not set the
> block would be skipped.
>
> > + if (likely(pool->alloc.count < PP_ALLOC_CACHE_SIZE)) {
> > + pool->alloc.cache[pool->alloc.count++] = page;
> > + pool->pages_state_hold_cnt++;
> > + trace_page_pool_state_hold(pool, page,
> > + pool->pages_state_hold_cnt);
> > + } else {
> > + put_page(page);
>
> If you are just calling put_page here aren't you leaking DMA mappings?
> Wouldn't you need to potentially unmap the page before you call
> put_page on it?
Oops, I completely missed that. Alexander is right here.
>
> > + }
> > + }
> > +out:
> > if ((pp_flags & PP_FLAG_DMA_MAP) &&
> > - unlikely(!page_pool_dma_map(pool, page))) {
> > - put_page(page);
> > + unlikely(!page_pool_dma_map(pool, first_page))) {
> > + put_page(first_page);
>
> I would probably move this block up and make it a part of the pp_order
> block above. Also since you are doing this in 2 spots it might make
> sense to look at possibly making this an inline function.
>
> > return NULL;
> > }
> >
> > /* Track how many pages are held 'in-flight' */
> > pool->pages_state_hold_cnt++;
> > - trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
> > + trace_page_pool_state_hold(pool, first_page, pool->pages_state_hold_cnt);
> >
> > /* When page just alloc'ed is should/must have refcnt 1. */
> > - return page;
> > + return first_page;
> > }
> >
> > /* For using page_pool replace: alloc_pages() API calls, but provide
> > --
> > 2.26.2
> >
Cheers
/Ilias
next prev parent reply other threads:[~2021-03-12 20:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 15:43 [PATCH 0/7 v4] Introduce a bulk order-0 page allocator with two in-tree users Mel Gorman
2021-03-12 15:43 ` [PATCH 1/7] mm/page_alloc: Move gfp_allowed_mask enforcement to prepare_alloc_pages Mel Gorman
2021-03-19 16:11 ` Vlastimil Babka
2021-03-19 17:49 ` Mel Gorman
2021-03-12 15:43 ` [PATCH 2/7] mm/page_alloc: Rename alloced to allocated Mel Gorman
2021-03-19 16:22 ` Vlastimil Babka
2021-03-12 15:43 ` [PATCH 3/7] mm/page_alloc: Add a bulk page allocator Mel Gorman
2021-03-19 18:18 ` Vlastimil Babka
2021-03-22 8:30 ` Mel Gorman
2021-03-12 15:43 ` [PATCH 4/7] SUNRPC: Set rq_page_end differently Mel Gorman
2021-03-12 15:43 ` [PATCH 5/7] SUNRPC: Refresh rq_pages using a bulk page allocator Mel Gorman
2021-03-12 18:44 ` Alexander Duyck
2021-03-12 19:22 ` Chuck Lever III
2021-03-13 12:59 ` Mel Gorman
2021-03-12 15:43 ` [PATCH 6/7] net: page_pool: refactor dma_map into own function page_pool_dma_map Mel Gorman
2021-03-12 15:43 ` [PATCH 7/7] net: page_pool: use alloc_pages_bulk in refill code path Mel Gorman
2021-03-12 19:44 ` Alexander Duyck
2021-03-12 20:05 ` Ilias Apalodimas [this message]
2021-03-15 13:39 ` Jesper Dangaard Brouer
2021-03-13 13:30 ` Mel Gorman
2021-03-17 16:31 ` [PATCH 0/7 v4] Introduce a bulk order-0 page allocator with two in-tree users Alexander Lobakin
2021-03-17 16:38 ` Jesper Dangaard Brouer
2021-03-17 16:52 ` Alexander Lobakin
2021-03-17 17:19 ` Jesper Dangaard Brouer
2021-03-17 22:25 ` Alexander Lobakin
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