Sunday, August 1, 2010

The publisher requires that PDF fonts are embedded so that documents can be printed everywhere; one or more of your document fonts are not embedded.

Compile the latex by first doing:
Latex
Bibtex (if u have a separate bibliography file)
Latex
Dvi -> PS
PS -> PDF.

Do not directly use:
DVI -> PDF.

This will solve the embedding issues.

Wednesday, May 19, 2010

Command for varying RTT

tc qdisc add dev eth0 root netem delay 100

100 is in milli seconds

Friday, April 30, 2010

Finding the location of TCP variants in Linux kernel

nightfall:~# echo "westwood" > /proc/sys/net/ipv4/tcp_congestion_control 
nightfall:~# cat /proc/sys/net/ipv4/tcp_congestion_control 
westwood
nightfall:~# 
A list of available modules can be found here:
nightfall:~# ls /lib/modules/`uname -r`/kernel/net/ipv4/
ip_gre.ko  netfilter   tcp_cubic.ko      tcp_htcp.ko   tcp_lp.ko        tcp_vegas.ko
ipip.ko    tcp_bic.ko  tcp_highspeed.ko  tcp_hybla.ko  tcp_scalable.ko  tcp_veno.ko
nightfall:~# 

Thursday, February 11, 2010

How to solve undefined reference to `__umoddi3'

Problem faced:

kernel/built-in.o: In function `getnstimeofday':
(.text+0xee36): undefined reference to `__umoddi3'
kernel/built-in.o: In function `do_gettimeofday':
(.text+0xeee1): undefined reference to `__udivdi3'
kernel/built-in.o: In function `do_gettimeofday':
(.text+0xeefe): undefined reference to `__umoddi3'
kernel/built-in.o: In function `do_timer':
(.text+0xfd88): undefined reference to `__udivdi3'
kernel/built-in.o: In function `do_timer':
(.text+0xfda5): undefined reference to `__umoddi3'
make: *** [.tmp_vmlinux1] Error 1

Solution:


---
 include/linux/time.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/include/linux/time.h b/include/linux/time.h
index 2091a19..d32ef0a 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -174,6 +174,10 @@ static inline void timespec_add_ns(struct timespec *a, u64 ns)
 {
  ns += a->tv_nsec;
  while(unlikely(ns >= NSEC_PER_SEC)) {
+  /* The following asm() prevents the compiler from
+   * optimising this loop into a modulo operation.  */
+  asm("" : "+r"(ns));       // Include this line in the file /include/linux/time.h
+
   ns -= NSEC_PER_SEC;
   a->tv_sec++;
  }
-- 
This patch prevents gcc form "optimizing" the while loop into a costly modulo.
operation

Thursday, February 4, 2010

Setting and Removing http_proxy in linux

1. For setting http_proxy
                export http_proxy="http://proxy:port/"

2. For unsetting
                  unset http_proxy=""

Removing http_proxy [ 407 proxy authentication required ] when using synaptic package manager:

Do the following:
1. Remove proxy from Preferences -> Network proxy [ use direct connection ]
2. Remove proxy from synaptic package manager -> preferences -> Network
3. use unset http_proxy
4. export http_proxy=""
           check if proxy is set or not by using: echo $http_proxy
Repeat steps (3) and (4) for ftp proxy also.


5. immediately do apt-get update once or twice
6. If still you get error [407 proxy authentication required]

    goto ~/.bashrc check if http_proxy is set if so remove it.

Please also check if you have changed the file sources.list in /etc/apt folder. If so reverse it back to the old version.
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