Re: [PATCH 2/2] ksmbd: smbd: change the default maximum read/write, receive size

From: Namjae Jeon <linkinjeon@kernel.org>
To: Hyunchul Lee <hyc.lee@gmail.com>
Cc: Steve French <smfrench@gmail.com>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	CIFS <linux-cifs@vger.kernel.org>
Subject: Re: [PATCH 2/2] ksmbd: smbd: change the default maximum read/write, receive size
Date: Tue, 18 Jan 2022 08:33:24 +0900	[thread overview]
Message-ID: <CAKYAXd8uQ4MG=y8_GqhAwPX0CVfk9EoEu=WZuO7+UCCYJ2RBDw@mail.gmail.com> (raw)
In-Reply-To: <CANFS6baREfEidN+FqZROiF+6QtOQ6FXae6f0L9EVKaUFK2L3hg@mail.gmail.com>

2022-01-10 10:37 GMT+09:00, Hyunchul Lee <hyc.lee@gmail.com>:
> 2022년 1월 9일 (일) 오후 9:56, Namjae Jeon <linkinjeon@kernel.org>님이 작성:
>>
>> 2022-01-09 15:44 GMT+09:00, Steve French <smfrench@gmail.com>:
>> > Do you have more detail on what the negotiated readsize/writesize
>> > would be for Windows clients with this size? for Linux clients?
>> Hyunchul, Please answer.
>>
>
> For a Linux client, if connected using smb-direct,
> the size will be 1048512. But connected with multichannel,
> the size will be 4MB instead of 1048512. And this causes
> problems because the read/write size is bigger than 1048512.
> It looks like a bug. I have to limit the ksmbd's SMB2 maximum
> read/write size for a test.
>
> For Windows clients, the actual read/write size is less than
> 1048512.
In the case of my Chelsio device, Need to set it to about
512K(512*1024 - 64) for it to work.
The 1048512 value seems insufficient to cover all devices. Is there
any other way to set the minimum read/write value? Calibrate this
minimum value by looking at
the device information? For example variables in ib_dev->attrs.

>
>> >
>> > It looked like it would still be 4MB at first glance (although in
>> > theory some Windows could do 8MB) ... I may have missed something
>> I understood that multiple-buffer descriptor support was required to
>> set a read/write size of 1MB or more. As I know, Hyunchul is currently
>> working on it.
>> It seems to be set to the smaller of max read/write size in smb-direct
>> negotiate and max read/write size in smb2 negotiate.
>>
>> Hyunchul, I have one question more, How did you get 1048512 setting value
>> ?
>> >
>
> I remember when the size was 1MB, Windows clients requested read/write with
> 1048512 and 64.
>
>> > On Sat, Jan 8, 2022 at 8:43 PM Namjae Jeon <linkinjeon@kernel.org>
>> > wrote:
>> >>
>> >> 2022-01-07 14:45 GMT+09:00, Hyunchul Lee <hyc.lee@gmail.com>:
>> >> > Due to restriction that cannot handle multiple
>> >> > buffer descriptor structures, decrease the maximum
>> >> > read/write size for Windows clients.
>> >> >
>> >> > And set the maximum fragmented receive size
>> >> > in consideration of the receive queue size.
>> >> >
>> >> > Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
>> >> Acked-by: Namjae Jeon <linkinjeon@kernel.org>
>> >
>> >
>> >
>> > --
>> > Thanks,
>> >
>> > Steve
>> >
>
>
>
> --
> Thanks,
> Hyunchul
>