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Message-ID: <Y70wTOn+W/gfyILa@hera>
Date: Tue, 10 Jan 2023 11:30:52 +0200
From: Ilias Apalodimas <ilias.apalodimas@...aro.org>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: Jesper Dangaard Brouer <hawk@...nel.org>, netdev@...r.kernel.org,
linux-mm@...ck.org, Shakeel Butt <shakeelb@...gle.com>
Subject: Re: [PATCH v2 05/24] page_pool: Start using netmem in allocation
path.
On Thu, Jan 05, 2023 at 09:46:12PM +0000, Matthew Wilcox (Oracle) wrote:
> Convert __page_pool_alloc_page_order() and __page_pool_alloc_pages_slow()
> to use netmem internally. This removes a couple of calls
> to compound_head() that are hidden inside put_page().
> Convert trace_page_pool_state_hold(), page_pool_dma_map() and
> page_pool_set_pp_info() to take a netmem argument.
>
> Saves 83 bytes of text in __page_pool_alloc_page_order() and 98 in
> __page_pool_alloc_pages_slow() for a total of 181 bytes.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
> include/trace/events/page_pool.h | 14 +++++------
> net/core/page_pool.c | 42 +++++++++++++++++---------------
> 2 files changed, 29 insertions(+), 27 deletions(-)
>
> diff --git a/include/trace/events/page_pool.h b/include/trace/events/page_pool.h
> index 113aad0c9e5b..d1237a7ce481 100644
> --- a/include/trace/events/page_pool.h
> +++ b/include/trace/events/page_pool.h
> @@ -67,26 +67,26 @@ TRACE_EVENT(page_pool_state_release,
> TRACE_EVENT(page_pool_state_hold,
>
> TP_PROTO(const struct page_pool *pool,
> - const struct page *page, u32 hold),
> + const struct netmem *nmem, u32 hold),
>
> - TP_ARGS(pool, page, hold),
> + TP_ARGS(pool, nmem, hold),
>
> TP_STRUCT__entry(
> __field(const struct page_pool *, pool)
> - __field(const struct page *, page)
> + __field(const struct netmem *, nmem)
> __field(u32, hold)
> __field(unsigned long, pfn)
> ),
>
> TP_fast_assign(
> __entry->pool = pool;
> - __entry->page = page;
> + __entry->nmem = nmem;
> __entry->hold = hold;
> - __entry->pfn = page_to_pfn(page);
> + __entry->pfn = netmem_pfn(nmem);
> ),
>
> - TP_printk("page_pool=%p page=%p pfn=0x%lx hold=%u",
> - __entry->pool, __entry->page, __entry->pfn, __entry->hold)
> + TP_printk("page_pool=%p netmem=%p pfn=0x%lx hold=%u",
> + __entry->pool, __entry->nmem, __entry->pfn, __entry->hold)
> );
>
> TRACE_EVENT(page_pool_update_nid,
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 437241aba5a7..4e985502c569 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -304,8 +304,9 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool,
> pool->p.dma_dir);
> }
>
> -static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
> +static bool page_pool_dma_map(struct page_pool *pool, struct netmem *nmem)
> {
> + struct page *page = netmem_page(nmem);
> dma_addr_t dma;
>
> /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
> @@ -328,12 +329,12 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
> }
>
> static void page_pool_set_pp_info(struct page_pool *pool,
> - struct page *page)
> + struct netmem *nmem)
> {
> - page->pp = pool;
> - page->pp_magic |= PP_SIGNATURE;
> + nmem->pp = pool;
> + nmem->pp_magic |= PP_SIGNATURE;
> if (pool->p.init_callback)
> - pool->p.init_callback(page, pool->p.init_arg);
> + pool->p.init_callback(netmem_page(nmem), pool->p.init_arg);
> }
>
> static void page_pool_clear_pp_info(struct netmem *nmem)
> @@ -345,26 +346,26 @@ static void page_pool_clear_pp_info(struct netmem *nmem)
> static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
> gfp_t gfp)
> {
> - struct page *page;
> + struct netmem *nmem;
>
> gfp |= __GFP_COMP;
> - page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
> - if (unlikely(!page))
> + nmem = page_netmem(alloc_pages_node(pool->p.nid, gfp, pool->p.order));
> + if (unlikely(!nmem))
> return NULL;
>
> if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
> - unlikely(!page_pool_dma_map(pool, page))) {
> - put_page(page);
> + unlikely(!page_pool_dma_map(pool, nmem))) {
> + netmem_put(nmem);
> return NULL;
> }
>
> alloc_stat_inc(pool, slow_high_order);
> - page_pool_set_pp_info(pool, page);
> + page_pool_set_pp_info(pool, nmem);
>
> /* 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);
> - return page;
> + trace_page_pool_state_hold(pool, nmem, pool->pages_state_hold_cnt);
> + return netmem_page(nmem);
> }
>
> /* slow path */
> @@ -398,18 +399,18 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
> * page element have not been (possibly) DMA mapped.
> */
> for (i = 0; i < nr_pages; i++) {
> - page = pool->alloc.cache[i];
> + struct netmem *nmem = page_netmem(pool->alloc.cache[i]);
> if ((pp_flags & PP_FLAG_DMA_MAP) &&
> - unlikely(!page_pool_dma_map(pool, page))) {
> - put_page(page);
> + unlikely(!page_pool_dma_map(pool, nmem))) {
> + netmem_put(nmem);
> continue;
> }
>
> - page_pool_set_pp_info(pool, page);
> - pool->alloc.cache[pool->alloc.count++] = page;
> + page_pool_set_pp_info(pool, nmem);
> + pool->alloc.cache[pool->alloc.count++] = netmem_page(nmem);
> /* Track how many pages are held 'in-flight' */
> pool->pages_state_hold_cnt++;
> - trace_page_pool_state_hold(pool, page,
> + trace_page_pool_state_hold(pool, nmem,
> pool->pages_state_hold_cnt);
> }
>
> @@ -421,7 +422,8 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
> page = NULL;
> }
>
> - /* When page just alloc'ed is should/must have refcnt 1. */
> + /* When page just allocated it should have refcnt 1 (but may have
> + * speculative references) */
> return page;
> }
>
> --
> 2.35.1
>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>
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