netdev - 答复: 答复: [PATCH] page_pool: mark unbound node page as reusable pages

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Date:   Thu, 5 Dec 2019 01:55:25 +0000
From:   "Li,Rongqing" <lirongqing@...du.com>
To:     Yunsheng Lin <linyunsheng@...wei.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "saeedm@...lanox.com" <saeedm@...lanox.com>
Subject: 答复: 答复: [PATCH] page_pool: mark unbound node page as reusable pages



> -----邮件原件-----
> 发件人: Yunsheng Lin [mailto:linyunsheng@...wei.com]
> 发送时间: 2019年12月5日 9:44
> 收件人: Li,Rongqing <lirongqing@...du.com>; netdev@...r.kernel.org;
> saeedm@...lanox.com
> 主题: Re: 答复: [PATCH] page_pool: mark unbound node page as reusable
> pages
> 
> On 2019/12/5 9:08, Li,Rongqing wrote:
> >
> >
> >> -----邮件原件-----
> >> 发件人: Yunsheng Lin [mailto:linyunsheng@...wei.com]
> >> 发送时间: 2019年12月5日 8:55
> >> 收件人: Li,Rongqing <lirongqing@...du.com>; netdev@...r.kernel.org;
> >> saeedm@...lanox.com
> >> 主题: Re: [PATCH] page_pool: mark unbound node page as reusable pages
> >>
> >> On 2019/12/4 18:14, Li RongQing wrote:
> >>> some drivers uses page pool, but not require to allocate page from
> >>> bound node, so pool.p.nid is NUMA_NO_NODE, and this fixed patch will
> >>> block this kind of driver to recycle
> >>>
> >>> Fixes: d5394610b1ba ("page_pool: Don't recycle non-reusable pages")
> >>> Signed-off-by: Li RongQing <lirongqing@...du.com>
> >>> Cc: Saeed Mahameed <saeedm@...lanox.com>
> >>> ---
> >>>  net/core/page_pool.c | 4 +++-
> >>>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c index
> >>> a6aefe989043..4054db683178 100644
> >>> --- a/net/core/page_pool.c
> >>> +++ b/net/core/page_pool.c
> >>> @@ -317,7 +317,9 @@ static bool __page_pool_recycle_direct(struct
> >>> page
> >> *page,
> >>>   */
> >>>  static bool pool_page_reusable(struct page_pool *pool, struct page
> >>> *page)  {
> >>> -	return !page_is_pfmemalloc(page) && page_to_nid(page) ==
> pool->p.nid;
> >>> +	return !page_is_pfmemalloc(page) &&
> >>> +		(page_to_nid(page) == pool->p.nid ||
> >>> +		 pool->p.nid == NUMA_NO_NODE);
> >>
> >> If I understand it correctly, you are allowing recycling when
> >> pool->p.nid is NUMA_NO_NODE, which does not seems match the commit
> >> log: "this fixed patch will block this kind of driver to recycle".
> >>
> >> Maybe you mean "commit d5394610b1ba" by this fixed patch?
> >
> > yes
> >
> >>
> >> Also, maybe it is better to allow recycling if the below condition is matched:
> >>
> >> 	pool->p.nid == NUMA_NO_NODE && page_to_nid(page) ==
> >> numa_mem_id()
> >
> > If driver uses NUMA_NO_NODE, it does not care numa node, and maybe its
> > platform Only has a node, so not need to compare like "page_to_nid(page) ==
> numa_mem_id()"
> 
> Normally, driver does not care if the node of a device is NUMA_NO_NODE or
> not, it just uses the node that returns from dev_to_node().
> 
> Even for multi node system, the node of a device may be NUMA_NO_NODE
> when BIOS/FW has not specified it through ACPI/DT, see [1].
> 
> 
> [1] https://lore.kernel.org/patchwork/patch/1141952/
> 

at this condition, page can be allocated from any node from driver boot,
why need to check "page_to_nid(page) == numa_mem_id()" at recycle?

-Li 

> >
> >
> > -RongQing
> >
> >
> >>
> >>>  }
> >>>
> >>>  void __page_pool_put_page(struct page_pool *pool, struct page
> >>> *page,
> >>>
> >