Re: [PATCH net-next v1 02/13] net: wwan: tmi: Add buffer management

[Yanchao Yang (杨彦超)]

Hello Sergey,

On Sun, 2022-12-04 at 22:58 +0400, Sergey Ryazanov wrote:
> On 22.11.2022 15:11, Yanchao Yang wrote:
> > From: MediaTek Corporation <linuxwwan@xxxxxxxxxxxx>
> > 
> > To malloc I/O memory as soon as possible, buffer management comes
> > into being.
> > It creates buffer pools that reserve some buffers through deferred
> > works when
> > the driver isn't busy.
> > 
> > The buffer management provides unified memory allocation/de-
> > allocation
> > interfaces for other modules. It supports two buffer types of SKB
> > and page.
> > Two reload work queues with different priority values are provided
> > to meet
> > various requirements of the control plane and the data plane.
> > 
> > When the reserved buffer count of the pool is less than a threshold
> > (default
> > is 2/3 of the pool size), the reload work will restart to allocate
> > buffers
> > from the OS until the buffer pool becomes full. When the buffer
> > pool fills,
> > the OS will recycle the buffer freed by the user.
> > 
> > Signed-off-by: Mingliang Xu <mingliang.xu@xxxxxxxxxxxx>
> > Signed-off-by: MediaTek Corporation <linuxwwan@xxxxxxxxxxxx>
> > ---
> >   drivers/net/wwan/mediatek/Makefile  |   3 +-
> >   drivers/net/wwan/mediatek/mtk_bm.c  | 369
> > ++++++++++++++++++++++++++++
> >   drivers/net/wwan/mediatek/mtk_bm.h  |  79 ++++++
> >   drivers/net/wwan/mediatek/mtk_dev.c |  11 +-
> >   drivers/net/wwan/mediatek/mtk_dev.h |   1 +
> >   5 files changed, 461 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/net/wwan/mediatek/mtk_bm.c
> >   create mode 100644 drivers/net/wwan/mediatek/mtk_bm.h
> 
> Yanchao, can you share some numbers, how this custom pool is
> outperform 
> the regular kernel allocator?
Prepare 2 drivers *.ko for comparison.
Driver A (following named A):  enable pre-allocate buffer pool.
Driver B (following named A):  disenable pre-allocate buffer pool. It
uses kernel API directly (__dev_alloc_skb and netdev_alloc_frag)

Test Instrument: Keysight UXM TA
Iperf command:
Server Command: iperf3 -s -p 5002 -i 1
Client Command: iperf3 -c 192.168.2.1 -p 5002 -i 1 -w 8M -t 30 -R -P 5

Test result: Fig 1. A’s TCP DL throughput Fig 2. B’s TCP DL throughput
(Ref attachment)

From the results, it represents that the A’s IP packets throughput
reaches 7Gbits/sec, while B’s throughput is 4.7Gbits/sec. A’s
throughput is up about 50% compared with B.

In addition, from ftrace, it represents following results.
A: it takes 14.241828s for allocating 33211099 buffers. The average
time is about 0.4us.
B: it takes 7.677069s for allocating 10890789 buffers. The average time
is about 0.7us.
> 
> --
> Sergey

many thanks.
Yanchao.Yang

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