On 12/10/24 03:40, Jakub Kicinski wrote:
On Wed, 4 Dec 2024 09:21:46 -0800 David Wei wrote:
+/*
+ * page_pool_mp_return_in_cache() - return a netmem to the allocation cache.
+ * @pool: pool from which pages were allocated
+ * @netmem: netmem to return
+ *
+ * Return already allocated and accounted netmem to the page pool's allocation
+ * cache. The function doesn't provide synchronisation and must only be called
+ * from the napi context.
NAPI is irrelevant, this helper, IIUC, has to be called down the call
chain from mp_ops->alloc().
+ */
+void page_pool_mp_return_in_cache(struct page_pool *pool, netmem_ref netmem)
+{
+ if (WARN_ON_ONCE(pool->alloc.count >= PP_ALLOC_CACHE_REFILL))
+ return;
I'd
return false;
without a warning.
+ page_pool_dma_sync_for_device(pool, netmem, -1);
+ page_pool_fragment_netmem(netmem, 1);
+ pool->alloc.cache[pool->alloc.count++] = netmem;
and here:
return true;
this say mps can use return value as a stop condition in a do {} while()
loop, without having to duplicate the check.
do {
netmem = alloc...
... logic;
} while (page_pool_mp_alloc_refill(pp, netmem));
/* last netmem didn't fit in the cache */
return netmem;
That last netmem is a problem. Returning it is not a bad option,
but it doesn't feel right. Providers should rather converge to
one way of returning buffers and batching here is needed.
I'd rather prefer this one then
while (pp_has_space()) {
netmem = alloc();
pp_push(netmem);
}
Any thoughts on that?
--
Pavel Begunkov
