@@ -2184,6 +2184,8 @@ static inline struct sk_buff *netdev_alloc_skb_ip_align(struct net_device *dev,
return __netdev_alloc_skb_ip_align(dev, length, GFP_ATOMIC);
}
+void *napi_alloc_frag(unsigned int fragsz);
+
/**
* __dev_alloc_pages - allocate page for network Rx
* @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
@@ -336,59 +336,60 @@ struct netdev_alloc_cache {
unsigned int pagecnt_bias;
};
static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
+static DEFINE_PER_CPU(struct netdev_alloc_cache, napi_alloc_cache);
-static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
+static void *__alloc_page_frag(struct netdev_alloc_cache __percpu *cache,
+ unsigned int fragsz, gfp_t gfp_mask)
{
- struct netdev_alloc_cache *nc;
- void *data = NULL;
- int order;
- unsigned long flags;
+ struct netdev_alloc_cache *nc = this_cpu_ptr(cache);
- local_irq_save(flags);
- nc = this_cpu_ptr(&netdev_alloc_cache);
if (unlikely(!nc->frag.page)) {
refill:
- for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) {
- gfp_t gfp = gfp_mask;
-
- if (order)
- gfp |= __GFP_COMP | __GFP_NOWARN;
- nc->frag.page = alloc_pages(gfp, order);
- if (likely(nc->frag.page))
- break;
- if (--order < 0)
- goto end;
+ nc->frag.size = NETDEV_FRAG_PAGE_MAX_SIZE;
+ nc->frag.page = alloc_pages_node(NUMA_NO_NODE,
+ gfp_mask |
+ __GFP_COMP |
+ __GFP_NOWARN,
+ NETDEV_FRAG_PAGE_MAX_ORDER);
+ if (unlikely(!nc->frag.page)) {
+ nc->frag.size = PAGE_SIZE;
+ nc->frag.page = alloc_pages_node(NUMA_NO_NODE,
+ gfp_mask, 0);
+ if (unlikely(!nc->frag.page))
+ return NULL;
}
- nc->frag.size = PAGE_SIZE << order;
+
/* Even if we own the page, we do not use atomic_set().
* This would break get_page_unless_zero() users.
*/
- atomic_add(NETDEV_PAGECNT_MAX_BIAS - 1,
- &nc->frag.page->_count);
+ atomic_add(NETDEV_PAGECNT_MAX_BIAS - 1, &nc->frag.page->_count);
nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS;
- nc->frag.offset = 0;
+ nc->frag.offset = nc->frag.size;
}
- if (nc->frag.offset + fragsz > nc->frag.size) {
- if (atomic_read(&nc->frag.page->_count) != nc->pagecnt_bias) {
- if (!atomic_sub_and_test(nc->pagecnt_bias,
- &nc->frag.page->_count))
- goto refill;
- /* OK, page count is 0, we can safely set it */
- atomic_set(&nc->frag.page->_count,
- NETDEV_PAGECNT_MAX_BIAS);
- } else {
- atomic_add(NETDEV_PAGECNT_MAX_BIAS - nc->pagecnt_bias,
- &nc->frag.page->_count);
- }
+ if (nc->frag.offset < fragsz) {
+ if (atomic_sub_return(nc->pagecnt_bias, &nc->frag.page->_count))
+ goto refill;
+
+ /* OK, page count is 0, we can safely set it */
+ atomic_set(&nc->frag.page->_count, NETDEV_PAGECNT_MAX_BIAS);
nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS;
- nc->frag.offset = 0;
+ nc->frag.offset = nc->frag.size;
}
- data = page_address(nc->frag.page) + nc->frag.offset;
- nc->frag.offset += fragsz;
+ nc->frag.offset -= fragsz;
nc->pagecnt_bias--;
-end:
+
+ return page_address(nc->frag.page) + nc->frag.offset;
+}
+
+static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
+{
+ unsigned long flags;
+ void *data;
+
+ local_irq_save(flags);
+ data = __alloc_page_frag(&netdev_alloc_cache, fragsz, gfp_mask);
local_irq_restore(flags);
return data;
}
@@ -406,6 +407,17 @@ void *netdev_alloc_frag(unsigned int fragsz)
}
EXPORT_SYMBOL(netdev_alloc_frag);
+static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
+{
+ return __alloc_page_frag(&napi_alloc_cache, fragsz, gfp_mask);
+}
+
+void *napi_alloc_frag(unsigned int fragsz)
+{
+ return __napi_alloc_frag(fragsz, GFP_ATOMIC | __GFP_COLD);
+}
+EXPORT_SYMBOL(napi_alloc_frag);
+
/**
* __netdev_alloc_skb - allocate an skbuff for rx on a specific device
* @dev: network device to receive on
This patch splits the netdev_alloc_frag function up so that it can be used on one of two page frag pools instead of being fixed on the netdev_alloc_cache. By doing this we can add a NAPI specific function __napi_alloc_frag that accesses a pool that is only used from softirq context. The advantage to this is that we do not need to call local_irq_save/restore which can be a significant savings. I also took the opportunity to refactor the core bits that were placed in __alloc_page_frag. First I updated the allocation to do either a 32K allocation or an order 0 page. Then I also rewrote the logic to work from the end of the page to the start. By doing this the size value doesn't have to be used unless we have run out of space for page fragments. Finally I cleaned up the atomic bits so that we just do an atomic_sub_return and if that returns 0 then we set the page->_count via an atomic_set. This way we can remove the extra conditional for the atomic_read since it would have led to an atomic_inc in the case of success anyway. Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com> --- include/linux/skbuff.h | 2 + net/core/skbuff.c | 86 +++++++++++++++++++++++++++--------------------- 2 files changed, 51 insertions(+), 37 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html