linux-kernel - Re: [PATCH net-next] avoid fragmenting page memory with netdev_alloc

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Date:   Wed, 24 Feb 2021 19:31:05 +0000
From:   Ronak Doshi <doshir@...are.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Todd Sabin <tsabin@...are.com>, Pv-drivers <Pv-drivers@...are.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Kevin Hao <haokexin@...il.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Marco Elver <elver@...gle.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Guillaume Nault <gnault@...hat.com>,
        Dongseok Yi <dseok.yi@...sung.com>,
        Yadu Kishore <kyk.segfault@...il.com>,
        open list <linux-kernel@...r.kernel.org>,
        Keerthana Kalyanasundaram <keerthanak@...are.com>
Subject: Re: [PATCH net-next] avoid fragmenting page memory with
 netdev_alloc_cache


On 2/11/21, 4:18 PM, "Ronak Doshi" <doshir@...are.com> wrote:
>    From: Todd Sabin <tsabin@...are.com>
>
>    Linux network stack uses an allocation page cache for skbs.  The
>   purpose is to reduce the number of page allocations that it needs to
>    make, and it works by allocating a group of pages, and then
>    sub-allocating skb memory from them.  When all skbs referencing the
>    shared pages are freed, then the block of pages is finally freed.
>
>    When these skbs are all freed close together in time, this works fine.
>    However, what can happen is that there are multiple nics (or multiple
>    rx-queues in a single nic), and the skbs are allocated to fill the rx
>    ring(s). If some nics or queues are far more active than others, the
>    entries in the less busy nic/queue may end up referencing a page
>    block, while all of the other packets that referenced that block of
>    pages are freed.
>
>    The result of this is that the memory used by an appliance for its rx
>    rings can slowly grow to be much greater than it was originally.
>
>    This patch fixes that by giving each vmxnet3 device a per-rx-queue page
>    cache.
>
>    Signed-off-by: Todd Sabin <tsabin@...are.com>
>    Signed-off-by: Ronak Doshi <doshir@...are.com>
>    ---
>     drivers/net/vmxnet3/vmxnet3_drv.c | 30 ++++++++++++++++++++++++------
>     drivers/net/vmxnet3/vmxnet3_int.h |  2 ++
>     include/linux/skbuff.h            |  2 ++
>     net/core/skbuff.c                 | 21 +++++++++++++++------
>     4 files changed, 43 insertions(+), 12 deletions(-)

Any update on this patch?

Thanks,
Ronak