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Re: Almost 80% of UDP packets dropped

To: "kernel coder" <>, <>
Subject: Re: Almost 80% of UDP packets dropped
From: "Kevin D. Kissell" <>
Date: Sat, 7 Jan 2006 10:24:29 +0100
Original-recipient: rfc822;
References: <>
What value of HZ are you using?  If you're still at the 2.6 default of 1000,
try reducing it to 100 and see if things improve...

----- Original Message ----- 
From: "kernel coder" <>
To: <>
Sent: Saturday, January 07, 2006 8:02 AM
Subject: Almost 80% of UDP packets dropped

> hi,
>     I was trying to measure the UDP reception speed on my borad which
> has MIPS 4kc processor with 133 MHZ speed.I was transfering 10mb file
> from intel pentium 4 machine to MIPS board,but the recieved file was
> only 900kB.
> When i further investigated the problem ,i came to know that the user
> application was not getting enough opportunities to get data from
> socket queue which caused almost 80% of packets to be dropped as
> socket queue had no free space.
> When i increased the socket recieve buffer size,it resulted in
> increase in no. of packets recieved .When i slow slowed down the
> transmitter , it also caused more packets to be recieved.
> But the above mentioned mechanism only decreased no. of lost
> packets.But there was no way that i could increase UDP reception speed
> because the user application was not getting enough opportunities to
> read packets in burst of UDP packets.
> I noticed that user application started recieveing packets after
> Kernel had recieved all the UDP packets.
> Please tell me how can i make sure that user application or udp client
> running MIPS 4kc processor gets enough opportunities to dequeue
> packets from socket buffer so that lost of packets could be reduced to
> minimal and also the size of UDP recieved file in a specific interval
> of time could be increased.
> lhrkernelcoder

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