From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5161AECE58E for ; Thu, 17 Oct 2019 08:52:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23F2A20663 for ; Thu, 17 Oct 2019 08:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408387AbfJQIwA (ORCPT ); Thu, 17 Oct 2019 04:52:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54468 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405250AbfJQIwA (ORCPT ); Thu, 17 Oct 2019 04:52:00 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8183D8AC6FB; Thu, 17 Oct 2019 08:51:59 +0000 (UTC) Received: from carbon (ovpn-200-46.brq.redhat.com [10.40.200.46]) by smtp.corp.redhat.com (Postfix) with ESMTP id 444D760852; Thu, 17 Oct 2019 08:51:53 +0000 (UTC) Date: Thu, 17 Oct 2019 10:51:52 +0200 From: Jesper Dangaard Brouer To: Jonathan Lemon Cc: , , , , , brouer@redhat.com Subject: Re: [PATCH 07/10 net-next] page_pool: allow configurable linear cache size Message-ID: <20191017105152.50e6ed36@carbon> In-Reply-To: <20191016225028.2100206-8-jonathan.lemon@gmail.com> References: <20191016225028.2100206-1-jonathan.lemon@gmail.com> <20191016225028.2100206-8-jonathan.lemon@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Thu, 17 Oct 2019 08:51:59 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 16 Oct 2019 15:50:25 -0700 Jonathan Lemon wrote: > Some drivers may utilize more than one page per RX work entry. > Allow a configurable cache size, with the same defaults if the > size is zero. > > Convert magic numbers into descriptive entries. > > Re-arrange the page_pool structure for efficiency. IMHO the re-arrange you did does not improve efficiency, it kills the efficiency... > Signed-off-by: Jonathan Lemon > --- > include/net/page_pool.h | 50 ++++++++++++++++++++--------------------- > net/core/page_pool.c | 49 +++++++++++++++++++++++----------------- > 2 files changed, 54 insertions(+), 45 deletions(-) > > diff --git a/include/net/page_pool.h b/include/net/page_pool.h > index 89bc91294b53..fc340db42f9a 100644 > --- a/include/net/page_pool.h > +++ b/include/net/page_pool.h > @@ -51,41 +51,34 @@ > * cache is already full (or partly full) then the XDP_DROP recycles > * would have to take a slower code path. > */ > -#define PP_ALLOC_CACHE_SIZE 128 > #define PP_ALLOC_CACHE_REFILL 64 > -struct pp_alloc_cache { > - u32 count; > - void *cache[PP_ALLOC_CACHE_SIZE]; > -}; > +#define PP_ALLOC_CACHE_DEFAULT (2 * PP_ALLOC_CACHE_REFILL) > +#define PP_ALLOC_CACHE_LIMIT 512 > +#define PP_ALLOC_POOL_DEFAULT 1024 > +#define PP_ALLOC_POOL_LIMIT 32768 > > struct page_pool_params { > unsigned int flags; > unsigned int order; > unsigned int pool_size; > + unsigned int cache_size; > int nid; /* Numa node id to allocate from pages from */ > - struct device *dev; /* device, for DMA pre-mapping purposes */ > enum dma_data_direction dma_dir; /* DMA mapping direction */ > + struct device *dev; /* device, for DMA pre-mapping purposes */ > }; > > struct page_pool { > struct page_pool_params p; > > + u32 alloc_count; > u32 pages_state_hold_cnt; > + atomic_t pages_state_release_cnt; The struct members pages_state_hold_cnt and pages_state_release_cnt, MUST be kept on different cachelines, else the point of tracking inflight pages this way is lost. > - /* > - * Data structure for allocation side > - * > - * Drivers allocation side usually already perform some kind > - * of resource protection. Piggyback on this protection, and > - * require driver to protect allocation side. > - * > - * For NIC drivers this means, allocate a page_pool per > - * RX-queue. As the RX-queue is already protected by > - * Softirq/BH scheduling and napi_schedule. NAPI schedule > - * guarantee that a single napi_struct will only be scheduled > - * on a single CPU (see napi_schedule). > + /* A page_pool is strictly tied to a single RX-queue being > + * protected by NAPI, due to above pp_alloc_cache. This ^^^^^^^^^^^^^^ You remove the 'pp_alloc_cache' in this patch, and still mention it in the comments. > + * refcnt serves purpose is to simplify drivers error handling. > */ > - struct pp_alloc_cache alloc ____cacheline_aligned_in_smp; > + refcount_t user_cnt; > > /* Data structure for storing recycled pages. > * > @@ -100,13 +93,20 @@ struct page_pool { > */ > struct ptr_ring ring; > > - atomic_t pages_state_release_cnt; > - > - /* A page_pool is strictly tied to a single RX-queue being > - * protected by NAPI, due to above pp_alloc_cache. This > - * refcnt serves purpose is to simplify drivers error handling. > + /* > + * Data structure for allocation side > + * > + * Drivers allocation side usually already perform some kind > + * of resource protection. Piggyback on this protection, and > + * require driver to protect allocation side. > + * > + * For NIC drivers this means, allocate a page_pool per > + * RX-queue. As the RX-queue is already protected by > + * Softirq/BH scheduling and napi_schedule. NAPI schedule > + * guarantee that a single napi_struct will only be scheduled > + * on a single CPU (see napi_schedule). > */ > - refcount_t user_cnt; > + void *alloc_cache[]; > }; > > struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > index ea56823236c5..f8fedecddb6f 100644 > --- a/net/core/page_pool.c > +++ b/net/core/page_pool.c > @@ -18,22 +18,18 @@ > > #include > > -static int page_pool_init(struct page_pool *pool, > - const struct page_pool_params *params) > +static int page_pool_init(struct page_pool *pool) > { > - unsigned int ring_qsize = 1024; /* Default */ > - > - memcpy(&pool->p, params, sizeof(pool->p)); > > /* Validate only known flags were used */ > if (pool->p.flags & ~(PP_FLAG_ALL)) > return -EINVAL; > > - if (pool->p.pool_size) > - ring_qsize = pool->p.pool_size; > + if (!pool->p.pool_size) > + pool->p.pool_size = PP_ALLOC_POOL_DEFAULT; > > /* Sanity limit mem that can be pinned down */ > - if (ring_qsize > 32768) > + if (pool->p.pool_size > PP_ALLOC_POOL_LIMIT) > return -E2BIG; > > /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL. > @@ -44,7 +40,7 @@ static int page_pool_init(struct page_pool *pool, > (pool->p.dma_dir != DMA_BIDIRECTIONAL)) > return -EINVAL; > > - if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0) > + if (ptr_ring_init(&pool->ring, pool->p.pool_size, GFP_KERNEL) < 0) > return -ENOMEM; > > atomic_set(&pool->pages_state_release_cnt, 0); > @@ -61,13 +57,26 @@ static int page_pool_init(struct page_pool *pool, > struct page_pool *page_pool_create(const struct page_pool_params *params) > { > struct page_pool *pool; > + u32 cache_size, size; > int err; > > - pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, params->nid); > + cache_size = params->cache_size; > + if (!cache_size) > + cache_size = PP_ALLOC_CACHE_DEFAULT; > + > + /* Sanity limit mem that can be pinned down */ > + if (cache_size > PP_ALLOC_CACHE_LIMIT) > + return ERR_PTR(-E2BIG); > + > + size = sizeof(*pool) + cache_size * sizeof(void *); > + pool = kzalloc_node(size, GFP_KERNEL, params->nid); You have now placed alloc_cache at the end of page_pool struct, this allows for dynamic changing the size, that is kind of nice. Before I placed pp_alloc_cache in struct to make sure that we didn't have false-sharing. Now, I'm unsure if false-sharing can happen? (depend on alignment from kzalloc_node). > if (!pool) > return ERR_PTR(-ENOMEM); > > - err = page_pool_init(pool, params); > + memcpy(&pool->p, params, sizeof(pool->p)); > + pool->p.cache_size = cache_size; > + > + err = page_pool_init(pool); > if (err < 0) { > pr_warn("%s() gave up with errno %d\n", __func__, err); > kfree(pool); > @@ -87,9 +96,9 @@ static struct page *__page_pool_get_cached(struct page_pool *pool) > > /* Test for safe-context, caller should provide this guarantee */ > if (likely(in_serving_softirq())) { > - if (likely(pool->alloc.count)) { > + if (likely(pool->alloc_count)) { > /* Fast-path */ > - page = pool->alloc.cache[--pool->alloc.count]; > + page = pool->alloc_cache[--pool->alloc_count]; > return page; > } > refill = true; > @@ -105,8 +114,8 @@ static struct page *__page_pool_get_cached(struct page_pool *pool) > spin_lock(&r->consumer_lock); > page = __ptr_ring_consume(r); > if (refill) > - pool->alloc.count = __ptr_ring_consume_batched(r, > - pool->alloc.cache, > + pool->alloc_count = __ptr_ring_consume_batched(r, > + pool->alloc_cache, > PP_ALLOC_CACHE_REFILL); > spin_unlock(&r->consumer_lock); > return page; > @@ -276,11 +285,11 @@ static bool __page_pool_recycle_into_ring(struct page_pool *pool, > static bool __page_pool_recycle_into_cache(struct page *page, > struct page_pool *pool) > { > - if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE)) > + if (unlikely(pool->alloc_count == pool->p.cache_size)) > return false; > > /* Caller MUST have verified/know (page_ref_count(page) == 1) */ > - pool->alloc.cache[pool->alloc.count++] = page; > + pool->alloc_cache[pool->alloc_count++] = page; > return true; > } > > @@ -365,7 +374,7 @@ void __page_pool_free(struct page_pool *pool) > if (!page_pool_put(pool)) > return; > > - WARN(pool->alloc.count, "API usage violation"); > + WARN(pool->alloc_count, "API usage violation"); > WARN(!ptr_ring_empty(&pool->ring), "ptr_ring is not empty"); > > /* Can happen due to forced shutdown */ > @@ -389,8 +398,8 @@ static void page_pool_flush(struct page_pool *pool) > * no-longer in use, and page_pool_alloc_pages() cannot be > * called concurrently. > */ > - while (pool->alloc.count) { > - page = pool->alloc.cache[--pool->alloc.count]; > + while (pool->alloc_count) { > + page = pool->alloc_cache[--pool->alloc_count]; > __page_pool_return_page(pool, page); > } > -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer