Messages in this thread | | | Subject | Re: [PATCH net-next v5 01/14] page_pool: make sure frag API fields don't span between cachelines | From | Yunsheng Lin <> | Date | Sat, 25 Nov 2023 20:29:22 +0800 |
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On 2023/11/24 23:47, Alexander Lobakin wrote: > After commit 5027ec19f104 ("net: page_pool: split the page_pool_params > into fast and slow") that made &page_pool contain only "hot" params at > the start, cacheline boundary chops frag API fields group in the middle > again. > To not bother with this each time fast params get expanded or shrunk, > let's just align them to `4 * sizeof(long)`, the closest upper pow-2 to > their actual size (2 longs + 2 ints). This ensures 16-byte alignment for > the 32-bit architectures and 32-byte alignment for the 64-bit ones, > excluding unnecessary false-sharing. > > Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> > --- > include/net/page_pool/types.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h > index e1bb92c192de..989d07b831fc 100644 > --- a/include/net/page_pool/types.h > +++ b/include/net/page_pool/types.h > @@ -127,7 +127,7 @@ struct page_pool { > > bool has_init_callback;
It seems odd to have only a slow field between tow fast field group, isn't it better to move it to the end of page_pool or where is more appropriate?
> > - long frag_users; > + long frag_users __aligned(4 * sizeof(long));
If we need that, why not just use '____cacheline_aligned_in_smp'?
> struct page *frag_page; > unsigned int frag_offset; > u32 pages_state_hold_cnt; >
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