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Message-ID: <ZbuFX2TQUQBovDy2@lore-desk>
Date: Thu, 1 Feb 2024 12:49:51 +0100
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
Cc: Yunsheng Lin <linyunsheng@...wei.com>, netdev@...r.kernel.org,
davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
pabeni@...hat.com, bpf@...r.kernel.org, toke@...hat.com,
willemdebruijn.kernel@...il.com, jasowang@...hat.com,
sdf@...gle.com, hawk@...nel.org, ilias.apalodimas@...aro.org
Subject: Re: [PATCH v6 net-next 1/5] net: add generic per-cpu page_pool
allocator
> > On 2024/1/29 21:04, Lorenzo Bianconi wrote:
> > >> On 2024/1/28 22:20, Lorenzo Bianconi wrote:
> > >>
> > >>> #ifdef CONFIG_LOCKDEP
> > >>> /*
> > >>> * register_netdevice() inits txq->_xmit_lock and sets lockdep class
> > >>> @@ -11686,6 +11690,27 @@ static void __init net_dev_struct_check(void)
> > >>> *
> > >>> */
> > >>>
> > >>> +#define SD_PAGE_POOL_RING_SIZE 256
> > >>
> > >> I might missed that if there is a reason we choose 256 here, do we
> > >> need to use different value for differe page size, for 64K page size,
> > >> it means we might need to reserve 16MB memory for each CPU.
> > >
> > > honestly I have not spent time on it, most of the current page_pool users set
> > > pool_size to 256. Anyway, do you mean something like:
> > >
> > > diff --git a/net/core/dev.c b/net/core/dev.c
> > > index f70fb6cad2b2..3934a3fc5c45 100644
> > > --- a/net/core/dev.c
> > > +++ b/net/core/dev.c
> > > @@ -11806,12 +11806,11 @@ static void __init net_dev_struct_check(void)
> > > *
> > > */
> > >
> > > -#define SD_PAGE_POOL_RING_SIZE 256
> > > static int net_page_pool_alloc(int cpuid)
> > > {
> > > #if IS_ENABLED(CONFIG_PAGE_POOL)
> >
> > Isn't better to have a config like CONFIG_PER_CPU_PAGE_POOL to enable
> > this feature? and this config can be selected by whoever needs this
> > feature?
>
> since it will be used for generic xdp (at least) I think this will be 99%
> enabled when we have bpf enabled, right?
>
> >
> > > struct page_pool_params page_pool_params = {
> > > - .pool_size = SD_PAGE_POOL_RING_SIZE,
> > > + .pool_size = PAGE_SIZE < SZ_64K ? 256 : 16,
> >
> > What about other page size? like 16KB?
> > How about something like below:
> > PAGE_SIZE << get_order(PER_CPU_PAGE_POOL_MAX_SIZE)
>
> since pool_size is the number of elements in the ptr_ring associated to the pool,
> assuming we want to consume PER_CPU_PAGE_POOL_MAX_SIZE for each cpu, something
> like:
>
> PER_CPU_PAGE_POOL_MAX_SIZE / PAGE_SIZE
>
> Regards,
> Lorenzo
Discussing with Jesper and Toke, we agreed page_pool infrastructure will need
a way to release memory when the system is under memory pressure, so we can
defer this item to a subsequent series, what do you think?
Regards,
Lorenzo
>
> >
> > > .nid = NUMA_NO_NODE,
> > > };
> > > struct page_pool *pp_ptr;
> >
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