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Subject: Re: [PATCH v3] pipe: use __pipe_{lock,unlock} instead of spinlock
To:     sedat.dilek@gmail.com
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        David Howells <dhowells@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        "Christian Brauner (Microsoft)" <brauner@kernel.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Eric Dumazet <edumazet@google.com>,
        "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230107012324.30698-1-zhanghongchen@loongson.cn>
 <9fcb3f80-cb55-9a72-0e74-03ace2408d21@loongson.cn>
 <CA+icZUU3-t0+NhdMQ39OeuwR13eMVOKVhLwS31WTHQ1ksaWgNg@mail.gmail.com>
 <CA+icZUXWAu_+KT9wYfdn7uSp1=ikO5ZdhM2VFokRi_JfhL455Q@mail.gmail.com>
From:   Hongchen Zhang <zhanghongchen@loongson.cn>
Message-ID: <c896b0f8-e172-625c-59f2-a78c745c92f6@loongson.cn>
Date:   Mon, 16 Jan 2023 10:16:36 +0800
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Hi sedat,


On 2023/1/16 am9:52, Sedat Dilek wrote:
> On Fri, Jan 13, 2023 at 10:32 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>>
>> On Fri, Jan 13, 2023 at 4:19 AM Hongchen Zhang
>> <zhanghongchen@loongson.cn> wrote:
>>>
>>> Hi All,
>>> any question about this patch, can it be merged?
>>>
>>> Thanks
>>> On 2023/1/7 am 9:23, Hongchen Zhang wrote:
>>>> Use spinlock in pipe_read/write cost too much time,IMO
>>>> pipe->{head,tail} can be protected by __pipe_{lock,unlock}.
>>>> On the other hand, we can use __pipe_{lock,unlock} to protect
>>>> the pipe->{head,tail} in pipe_resize_ring and
>>>> post_one_notification.
>>>>
>>>> Reminded by Matthew, I tested this patch using UnixBench's pipe
>>>> test case on a x86_64 machine,and get the following data:
>>>> 1) before this patch
>>>> System Benchmarks Partial Index  BASELINE       RESULT    INDEX
>>>> Pipe Throughput                   12440.0     493023.3    396.3
>>>>                                                           ========
>>>> System Benchmarks Index Score (Partial Only)              396.3
>>>>
>>>> 2) after this patch
>>>> System Benchmarks Partial Index  BASELINE       RESULT    INDEX
>>>> Pipe Throughput                   12440.0     507551.4    408.0
>>>>                                                           ========
>>>> System Benchmarks Index Score (Partial Only)              408.0
>>>>
>>>> so we get ~3% speedup.
>>>>
>>>> Reminded by Andrew, I tested this patch with the test code in
>>>> Linus's 0ddad21d3e99 add get following result:
>>
>> Happy new 2023 Hongchen Zhang,
>>
>> Thanks for the update and sorry for the late response.
>>
>> Should be "...s/add/and get following result:"
>>
>> I cannot say much about the patch itself or tested it in my build-environment.
>>
>> Best regards,
>> -Sedat-
>>
> 
> I have applied v3 on top of Linux v6.2-rc4.
> 
> Used pipebench for a quick testing.
> 
> # fdisk -l /dev/sdb
> Disk /dev/sdb: 14,91 GiB, 16013942784 bytes, 31277232 sectors
> Disk model: SanDisk iSSD P4
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x74f02dea
> 
> Device     Boot Start      End  Sectors  Size Id Type
> /dev/sdb1        2048 31277231 31275184 14,9G 83 Linux
> 
> # cat /dev/sdb | pipebench > /dev/null
> Summary:
> Piped   14.91 GB in 00h01m34.20s:  162.12 MB/second
> 
> Not tested/benchmarked with the kernel w/o your patch.
> 
> -Sedat-
> 
OK, If there is any problem, let's continue to discuss it
and hope it can be merged into the main line.

Best Regards,
Hongchen Zhang