by Ilias Apalodimas

[permalink] [raw]

Subject: Re: [PATCH net-next v6 06/12] page_pool: constify some read-only function arguments

Apologies for the noise,
Resending without HTML

On Thu, 7 Dec 2023 at 19:22, Alexander Lobakin
<[email protected]> wrote:
>
> There are several functions taking pointers to data they don't modify.
> This includes statistics fetching, page and page_pool parameters, etc.
> Constify the pointers, so that call sites will be able to pass const
> pointers as well.
> No functional changes, no visible changes in functions sizes.
>
> Signed-off-by: Alexander Lobakin <[email protected]>
> ---
> include/net/page_pool/helpers.h | 10 +++++-----
> net/core/page_pool.c | 8 ++++----
> 2 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
> index 7dc65774cde5..c860fad50d00 100644
> --- a/include/net/page_pool/helpers.h
> +++ b/include/net/page_pool/helpers.h
> @@ -58,7 +58,7 @@
> /* Deprecated driver-facing API, use netlink instead */
> int page_pool_ethtool_stats_get_count(void);
> u8 *page_pool_ethtool_stats_get_strings(u8 *data);
> -u64 *page_pool_ethtool_stats_get(u64 *data, void *stats);
> +u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats);
>
> bool page_pool_get_stats(const struct page_pool *pool,
> struct page_pool_stats *stats);
> @@ -73,7 +73,7 @@ static inline u8 *page_pool_ethtool_stats_get_strings(u8 *data)
> return data;
> }
>
> -static inline u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
> +static inline u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats)
> {
> return data;
> }
> @@ -204,8 +204,8 @@ static inline void *page_pool_dev_alloc_va(struct page_pool *pool,
> * Get the stored dma direction. A driver might decide to store this locally
> * and avoid the extra cache line from page_pool to determine the direction.
> */
> -static
> -inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
> +static inline enum dma_data_direction
> +page_pool_get_dma_dir(const struct page_pool *pool)
> {
> return pool->p.dma_dir;
> }
> @@ -357,7 +357,7 @@ static inline void page_pool_free_va(struct page_pool *pool, void *va,
> * Fetch the DMA address of the page. The page pool to which the page belongs
> * must had been created with PP_FLAG_DMA_MAP.
> */
> -static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
> +static inline dma_addr_t page_pool_get_dma_addr(const struct page *page)
> {
> dma_addr_t ret = page->dma_addr;
>
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 59aca3339222..4295aec0be40 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -121,9 +121,9 @@ int page_pool_ethtool_stats_get_count(void)
> }
> EXPORT_SYMBOL(page_pool_ethtool_stats_get_count);
>
> -u64 *page_pool_ethtool_stats_get(u64 *data, void *stats)
> +u64 *page_pool_ethtool_stats_get(u64 *data, const void *stats)
> {
> - struct page_pool_stats *pool_stats = stats;
> + const struct page_pool_stats *pool_stats = stats;
>
> *data++ = pool_stats->alloc_stats.fast;
> *data++ = pool_stats->alloc_stats.slow;
> @@ -360,8 +360,8 @@ static struct page *__page_pool_get_cached(struct page_pool *pool)
> return page;
> }
>
> -static void page_pool_dma_sync_for_device(struct page_pool *pool,
> - struct page *page,
> +static void page_pool_dma_sync_for_device(const struct page_pool *pool,
> + const struct page *page,
> unsigned int dma_sync_size)
> {
> dma_addr_t dma_addr = page_pool_get_dma_addr(page);
> --
> 2.43.0
>

Reviewed-by: Ilias Apalodimas <[email protected]>

2023-12-13 11:25:33

by Alexander Lobakin

[permalink] [raw]

Subject: Re: [Intel-wired-lan] [PATCH net-next v6 08/12] libie: add Rx buffer management (via Page Pool)

From: Jakub Kicinski <[email protected]>
Date: Mon, 11 Dec 2023 11:23:32 -0800

> On Mon, 11 Dec 2023 11:16:20 +0100 Alexander Lobakin wrote:
>> Ideally, I'd like to pass a CPU ID this queue will be run on and use
>> cpu_to_node(), but currently there's no NUMA-aware allocations in the
>> Intel drivers and Rx queues don't get the corresponding CPU ID when
>> configuring. I may revisit this later, but for now NUMA_NO_NODE is the
>> most optimal solution here.
>
> Hm, I've been wondering about persistent IRQ mappings. Drivers
> resetting IRQ mapping on reconfiguration is a major PITA in production
> clusters. You change the RSS hash and some NICs suddenly forget
> affinitization ????️
>
> The connection with memory allocations changes the math on that a bit.
>
> The question is really whether we add CPU <> NAPI config as a netdev
> Netlink API or build around the generic IRQ affinity API. The latter
> is definitely better from "don't duplicate uAPI" perspective.
> But we need to reset the queues and reallocate their state when
> the mapping is changed. And shutting down queues on
>
> echo $cpu > /../smp_affinity_list
>
> seems moderately insane. Perhaps some middle-ground exists.
>
> Anyway, if you do find cycles to tackle this - pls try to do it
> generically not just for Intel? :)

Sounds good, adding to my fathomless backlog :>

Thanks,
Olek