From: Bob Liu <bob.liu@oracle.com>
To: Hou Tao <houtao1@huawei.com>,
linux-block@vger.kernel.org, bpf@vger.kernel.org,
netdev@vger.kernel.org, axboe@kernel.dk, ast@kernel.org
Cc: hare@suse.com, osandov@fb.com, ming.lei@redhat.com,
damien.lemoal@wdc.com, bvanassche@acm.org, daniel@iogearbox.net,
kafai@fb.com, songliubraving@fb.com, yhs@fb.com
Subject: Re: [RFC PATCH 0/2] block: use eBPF to redirect IO completion
Date: Tue, 15 Oct 2019 09:20:00 +0800 [thread overview]
Message-ID: <68fd4fe2-7008-4d7c-b8a6-dc7906dcd291@oracle.com> (raw)
In-Reply-To: <20191014122833.64908-1-houtao1@huawei.com>
On 10/14/19 8:28 PM, Hou Tao wrote:
> For network stack, RPS, namely Receive Packet Steering, is used to
> distribute network protocol processing from hardware-interrupted CPU
> to specific CPUs and alleviating soft-irq load of the interrupted CPU.
>
> For block layer, soft-irq (for single queue device) or hard-irq
> (for multiple queue device) is used to handle IO completion, so
> RPS will be useful when the soft-irq load or the hard-irq load
> of a specific CPU is too high, or a specific CPU set is required
> to handle IO completion.
>
> Instead of setting the CPU set used for handling IO completion
> through sysfs or procfs, we can attach an eBPF program to the
> request-queue, provide some useful info (e.g., the CPU
> which submits the request) to the program, and let the program
> decides the proper CPU for IO completion handling.
>
But it looks like there isn't any benefit than through sysfs/procfs?
> In order to demonostrate the effect of IO completion redirection,
> a test programm is built to redirect the IO completion handling
> to all online CPUs or a specific CPU set:
>
> ./test_blkdev_ccpu -d /dev/vda
> or
> ./test_blkdev_ccpu -d /dev/nvme0n1 -s 4,8,10-13
>
> However I am still trying to find out a killer scenario for
Speaking about scenario, perhaps attaching a filter could be useful?
So that the data can be processed the first place.
-
Bob
> the eBPF redirection, so suggestions and comments are welcome.
>
> Regards,
> Tao
>
> Hou Tao (2):
> block: add support for redirecting IO completion through eBPF
> selftests/bpf: add test program for redirecting IO completion CPU
>
> block/Makefile | 2 +-
> block/blk-bpf.c | 127 +++++++++
> block/blk-mq.c | 22 +-
> block/blk-softirq.c | 27 +-
> include/linux/blkdev.h | 3 +
> include/linux/bpf_blkdev.h | 9 +
> include/linux/bpf_types.h | 1 +
> include/uapi/linux/bpf.h | 2 +
> kernel/bpf/syscall.c | 9 +
> tools/include/uapi/linux/bpf.h | 2 +
> tools/lib/bpf/libbpf.c | 1 +
> tools/lib/bpf/libbpf_probes.c | 1 +
> tools/testing/selftests/bpf/Makefile | 1 +
> .../selftests/bpf/progs/blkdev_ccpu_rr.c | 66 +++++
> .../testing/selftests/bpf/test_blkdev_ccpu.c | 246 ++++++++++++++++++
> 15 files changed, 507 insertions(+), 12 deletions(-)
> create mode 100644 block/blk-bpf.c
> create mode 100644 include/linux/bpf_blkdev.h
> create mode 100644 tools/testing/selftests/bpf/progs/blkdev_ccpu_rr.c
> create mode 100644 tools/testing/selftests/bpf/test_blkdev_ccpu.c
>
prev parent reply other threads:[~2019-10-15 1:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 12:28 [RFC PATCH 0/2] block: use eBPF to redirect IO completion Hou Tao
2019-10-14 12:28 ` [RFC PATCH 1/2] block: add support for redirecting IO completion through eBPF Hou Tao
2019-10-15 21:04 ` Alexei Starovoitov
2019-10-16 7:05 ` Hannes Reinecke
2019-10-21 13:42 ` Hou Tao
2019-10-21 13:48 ` Bart Van Assche
2019-10-21 14:45 ` Jens Axboe
2019-10-14 12:28 ` [RFC PATCH 2/2] selftests/bpf: add test program for redirecting IO completion CPU Hou Tao
2019-10-15 1:20 ` Bob Liu [this message]
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