[PATCH net-next] net: page_pool: scale alloc cache with PAGE_SIZE

[PATCH net-next] net: page_pool: scale alloc cache with PAGE_SIZE

[Nimrod Oren]

The current page_pool alloc-cache size and refill values were chosen to
match the NAPI budget and to leave headroom for XDP_DROP recycling.
These fixed values do not scale well with large pages,
as they significantly increase a given page_pool's memory footprint.

Scale these values to better balance memory footprint across page sizes,
while keeping behavior on 4KB-page systems unchanged.

Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Nimrod Oren <noren@nvidia.com>
---

Changes since RFC [1]:
- Converted from RFC to PATCH
- Scale defines instead of dynamically capping values

[1] RFC: https://lore.kernel.org/20260223092410.2149014-1-noren@nvidia.com/

---
 include/net/page_pool/types.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 0d453484a585..08ffa766c26d 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -44,6 +44,8 @@
  * use-case.  The NAPI budget is 64 packets.  After a NAPI poll the RX
  * ring is usually refilled and the max consumed elements will be 64,
  * thus a natural max size of objects needed in the cache.
+ * The refill watermark is set to 64 for 4KB pages,
+ * and scales to balance its size in bytes across page sizes.
  *
  * Keeping room for more objects, is due to XDP_DROP use-case.  As
  * XDP_DROP allows the opportunity to recycle objects directly into
@@ -51,8 +53,15 @@
  * 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
+#if PAGE_SIZE >= SZ_64K
+#define PP_ALLOC_CACHE_REFILL	4
+#elif PAGE_SIZE >= SZ_16K
+#define PP_ALLOC_CACHE_REFILL	16
+#else
 #define PP_ALLOC_CACHE_REFILL	64
+#endif
+
+#define PP_ALLOC_CACHE_SIZE	(PP_ALLOC_CACHE_REFILL * 2)
 struct pp_alloc_cache {
 	u32 count;
 	netmem_ref cache[PP_ALLOC_CACHE_SIZE];
-- 
2.45.0

Re: [PATCH net-next] net: page_pool: scale alloc cache with PAGE_SIZE

[Jakub Kicinski]

On Mon, 9 Mar 2026 10:13:01 +0200 Nimrod Oren wrote:
> The current page_pool alloc-cache size and refill values were chosen to
> match the NAPI budget and to leave headroom for XDP_DROP recycling.
> These fixed values do not scale well with large pages,
> as they significantly increase a given page_pool's memory footprint.
> 
> Scale these values to better balance memory footprint across page sizes,
> while keeping behavior on 4KB-page systems unchanged.

Jesper WDYT? I'm of course happy with this simple approach.
https://lore.kernel.org/all/20260309081301.103152-1-noren@nvidia.com/

Re: [PATCH net-next] net: page_pool: scale alloc cache with PAGE_SIZE

[Jesper Dangaard Brouer]

On 12/03/2026 01.56, Jakub Kicinski wrote:
> On Mon, 9 Mar 2026 10:13:01 +0200 Nimrod Oren wrote:
>> The current page_pool alloc-cache size and refill values were chosen to
>> match the NAPI budget and to leave headroom for XDP_DROP recycling.
>> These fixed values do not scale well with large pages,
>> as they significantly increase a given page_pool's memory footprint.
>>
>> Scale these values to better balance memory footprint across page sizes,
>> while keeping behavior on 4KB-page systems unchanged.
> 
> Jesper WDYT? I'm of course happy with this simple approach.
> https://lore.kernel.org/all/20260309081301.103152-1-noren@nvidia.com/

Sorry for the slow response, LGTM.
Patch is already applied.

--Jesper

Re: [PATCH net-next] net: page_pool: scale alloc cache with PAGE_SIZE

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 9 Mar 2026 10:13:01 +0200 you wrote:
> The current page_pool alloc-cache size and refill values were chosen to
> match the NAPI budget and to leave headroom for XDP_DROP recycling.
> These fixed values do not scale well with large pages,
> as they significantly increase a given page_pool's memory footprint.
> 
> Scale these values to better balance memory footprint across page sizes,
> while keeping behavior on 4KB-page systems unchanged.
> 
> [...]

Here is the summary with links:
  - [net-next] net: page_pool: scale alloc cache with PAGE_SIZE
    https://git.kernel.org/netdev/net-next/c/15abbe7c8266

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html