All of lore.kernel.org
 help / color / mirror / Atom feed
From: sdrb@onet.eu
To: netdev@vger.kernel.org
Subject: Variable download speed
Date: Tue, 23 Feb 2016 12:19:58 +0100 (CET)	[thread overview]
Message-ID: <alpine.LNX.2.20.1602231216240.29937@localhost.localdomain> (raw)

Hi,

I've got a problem with network on one of my embedded boards.
I'm testing download speed of 256MB file from my PC to embedded board 
through 1Gbit ethernet link using ftp.

The problem is that sometimes I achieve 25MB/s and sometimes it is only 
14MB/s. There are also situations where the transfer speed starts at 
14MB/s and after a few seconds achieves 25MB/s.
I've caught the second case with tcpdump and I noticed that when the speed 
is 14MB/s - the tcp window size is 534368 bytes and when the speed 
achieved 25MB/s the tcp window size is 933888.

My question is: what causes such dynamic change in the window size (while 
transferring data)?  Is it some kernel parameter wrong set or something 
like this?
Do I have any influence on such dynamic change in tcp window size?

sdrb

             reply	other threads:[~2016-02-23 11:28 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-23 11:19 sdrb [this message]
2016-02-23 13:28 ` Variable download speed Neal Cardwell
2016-02-23 13:57   ` sdrb
2016-02-23 14:26     ` Neal Cardwell
2016-02-24  7:48       ` sdrb
2016-02-23 11:24 sdrb
2016-02-23 16:53 ` Rick Jones
2016-02-24  9:59   ` sdrb

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=alpine.LNX.2.20.1602231216240.29937@localhost.localdomain \
    --to=sdrb@onet.eu \
    --cc=netdev@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.