Date: Tue, 29 Aug 2023 10:28:57 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Wei Hu <weh@microsoft.com> Cc: Guido Falsi <mad@madpilot.net>, Mikhail Zakharov <zmey20000@yahoo.com>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: Very slow scp performance comparing to Linux Message-ID: <CAGudoHHWkVrkUMjYfft22MZxygGg4Aa9t=hfXdmaE1AUb6cxTA@mail.gmail.com> In-Reply-To: <SI2P153MB04418D609BBB9184FD7FFC4ABBE7A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM> References: <SI2P153MB0441858EC3FE24D5B7A6B34DBBE0A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM> <6952b7fd-f90f-2677-1997-d0c708cb559e@yahoo.com> <SI2P153MB04412D004F9930203B04A032BBE0A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM> <455dc69a-dd15-18d9-8e93-91bbff3997e4@madpilot.net> <SI2P153MB04418D609BBB9184FD7FFC4ABBE7A@SI2P153MB0441.APCP153.PROD.OUTLOOK.COM>
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On 8/29/23, Wei Hu <weh@microsoft.com> wrote:
>
>
>> -----Original Message-----
>> From: Guido Falsi <mad@madpilot.net>
>> Sent: Monday, August 28, 2023 6:49 PM
>> To: Wei Hu <weh@microsoft.com>; Mikhail Zakharov
>> <zmey20000@yahoo.com>; freebsd-hackers@freebsd.org
>> Subject: Re: Very slow scp performance comparing to Linux
>>
>> On 28/08/23 12:03, Wei Hu wrote:
>> > Hi Mike,
>> >
>> > All VMs are with same type and they are in Azure. If the copy on Linux
>> > is
>> being cached on the RX side, so is FreeBSD?
>> >
>>
>> You could perform the test using files in memory filesystems (tmpfs or
>> the
>> like). This would factor out disk performance whatever the backend.
>>
> Thanks, Guido. I tried tmpfs on the RX side with both FreeBSD and Linux VMs.
>
> The throughput on FreeBSD went up significantly from 50 MB/s to 630 MB/s
> with
> NIC interface. Linux went up modestly form 550 MB/s to 660 MB/s.
>
> So, looks in the non-tmpfs case, the Linux ext4 filesystem does cache large
> amounts
> of data in memory, much larger than FreeBSD ufs.
>
> Many thanks, Mike for bringing this up and Guido, for the suggestion to try
> tmpfs.
>
There is probably something funky going on here.
Here is a hack which will collect basic profiling info, works in a vm:
dtrace -w -n 'profile:::profile-4999 { @[sym(arg0)] = count(); }
tick-10s { system("clear"); trunc(@, 40); printa("%40a %@16d\n", @);
clear(@); }'
so start scp, start dtrace and see what happens
--
Mateusz Guzik <mjguzik gmail.com>
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