Hello, this is a patch with some updates to the Documetation/proc.txt
file, basically it contains updates to the new files in /proc/<PID>, new
files in /proc, and a paragraph about /proc/sys/net/ipv4/tcp_ecn. It's
far from complete, but it's a start point.
--- old/proc.txt Mon Oct 23 15:20:00 2000
+++ new/proc.txt Mon Nov 13 00:20:24 2000
@@ -46,7 +46,7 @@
the SuSE Linux distribution. As there is no complete documentation
for the
/proc file system and we've used many freely available sources to
write these
chapters, it seems only fair to give the work back to the Linux
community.
-This work is based on the 2.2.* kernel version. I'm afraid it's still
far from
+This work is based on the 2.2.* kernel version and the upcomming 2.4.*.
I'm afraid it's still far from
complete, but we hope it will be useful. As far as we know, it is
the first
'all-in-one' document about the /proc file system. It is focused on
the Intel
x86 hardware, so if you are looking for PPC, ARM, SPARC, APX, etc.,
features,
@@ -92,7 +92,7 @@
The proc file system acts as an interface to internal data structures
in the
kernel. It can be used to obtain information about the system and to
change
-certain kernel parameters at runtime.
+certain kernel parameters at runtime (sysctl).
First, we'll take a look at the read-only parts of /proc. In
Chapter 2, we
show you how you can use /proc/sys to change settings.
@@ -111,16 +111,17 @@
..............................................................................
File Content
cmdline Command line arguments
- environ Values of environment variables
+ cpu Current and last cpu in wich it was executed (2.4)(smp)
+ cwd Link to the Current Working Directory
+ environ Values of environment variables
+ exe Link to the executable in the filesystem
fd Directory, which contains all file descriptors
+ maps Maps to executables and library files (2.4)
mem Memory held by this process
+ root Link to the root directory of this process
stat Process status
- status Process status in human readable form
- cwd Link to the current working directory
- exe Link to the executable of this process
- maps Memory maps
- root Link to the root directory of this process
statm Process memory status information
+ status Process status in human readable form
..............................................................................
For example, to get the status information of a process, all you have
to do is
@@ -131,6 +132,7 @@
State: R (running)
Pid: 5452
PPid: 743
+ TracerPid: 0 (2.4)
Uid: 501 501 501 501
Gid: 100 100 100 100
Groups: 100 14 16
@@ -187,13 +189,20 @@
devices Available devices (block and character)
dma Used DMS channels
filesystems Supported filesystems
+ driver Various drivers grouped here, currently rtc (2.4)
+ execdomains Execdomains, related to security (2.4)
+ fb Frame Buffer devices (2.4)
+ fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
interrupts Interrupt usage
+ iomem Memory map (2.4)
ioports I/O port usage
- kcore Kernel core image (can be ELF or A.OUT)
+ irq Masks for irq to cpu affinity (2.4)(smp?)
+ isapnp ISA PnP (Plug&Play) Info (2.4)
+ kcore Kernel core image (can be ELF or A.OUT(depreciated in
2.4))
kmsg Kernel messages
ksyms Kernel symbol table
- loadavg Load average
+ loadavg Load average of last 1, 5 & 15 minutes
locks Kernel locks
meminfo Memory info
misc Miscellaneous
@@ -201,14 +210,19 @@
mounts Mounted filesystems
net Networking info (see text)
partitions Table of partitions known to the system
+ pci Depreciated info of PCI bus (new way -> /proc/bus/pci/,
+ decoupled by lspci (2.4)
rtc Real time clock
scsi SCSI info (see text)
slabinfo Slab pool info
stat Overall statistics
swaps Swap space utilization
sys See chapter 2
+ sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
+ tty Info of tty drivers
uptime System uptime
version Kernel version
+ video bttv info of video resources (2.4)
..............................................................................
You can, for example, check which interrupts are currently in use
and what
@@ -230,6 +244,68 @@
15: 7 XT-PIC ide1
NMI: 0
+In 2.4.* a couple of lines where added to this file LOC & ERR (this
time is the
+output of a SMP machine):
+
+ > cat /proc/interrupts
+
+ CPU0 CPU1
+ 0: 1243498 1214548 IO-APIC-edge timer
+ 1: 8949 8958 IO-APIC-edge keyboard
+ 2: 0 0 XT-PIC cascade
+ 5: 11286 10161 IO-APIC-edge soundblaster
+ 8: 1 0 IO-APIC-edge rtc
+ 9: 27422 27407 IO-APIC-edge 3c503
+ 12: 113645 113873 IO-APIC-edge PS/2 Mouse
+ 13: 0 0 XT-PIC fpu
+ 14: 22491 24012 IO-APIC-edge ide0
+ 15: 2183 2415 IO-APIC-edge ide1
+ 17: 30564 30414 IO-APIC-level eth0
+ 18: 177 164 IO-APIC-level bttv
+ NMI: 2457961 2457959
+ LOC: 2457882 2457881
+ ERR: 2155
+
+NMI is incremented in this case because every timer interrupt generates
a NMI
+(Non Maskable Interrupt) which is used by the NMI Watchdog to detect
lookups.
+
+LOC is the local interrupt counter of the internal APIC of every CPU.
+
+ERR is incremented in the case of errors in the IO-APIC bus (the bus
that
+connects the CPUs in a SMP system. This means that an error has been
detected,
+the IO-APIC automatically retry the transmision, so it should not be a
big
+problem, but you should read the SMP-FAQ.
+
+In this context it could be interesting to note the new irq directory
in 2.4.
+It could be used to set IRQ to CPU affinity, this means that you can
"hook" an
+IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents
of the
+irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask
+
+For example
+ > ls /proc/irq/
+ 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
+ 1 11 13 15 17 19 3 5 7 9
+ > ls /proc/irq/0/
+ smp_affinity
+
+The contents of the prof_cpu_mask file and each smp_affinity file for
each IRQ
+is the same by default:
+
+ > cat /proc/irq/0/smp_affinity
+ ffffffff
+
+It's a bitmask, in wich you can specify wich CPUs can handle the IRQ,
you can
+set it by doing:
+
+ > echo 1 > /proc/irq/prof_cpu_mask
+
+This means that only the first CPU will handle the IRQ, but you can
also echo 5
+wich means that only the first and fourth CPU can handle the IRQ.
+
+The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
+between all the CPUs which are allowed to handle it. As usual the
kernel has
+more info than you and does a better job than you, so the defaults are
the
+best choice for almost everyone.
There are three more important subdirectories in /proc: net, scsi,
and sys.
The general rule is that the contents, or even the existence
of these
@@ -1306,6 +1382,15 @@
TCP settings
------------
+
+tcp_ecn
+-------
+
+This file controls the use of the ECN bit in the IPv4 headers, this is
a new
+feature about Explicit Congestion Notification, but some routers and
firewalls
+block trafic that has this bit set, so it could be necessary to echo 0
to
+/proc/sys/net/ipv4/tcp_ecn, if you want to talk to this sites. For more
info
+you could read RFC2481.
tcp_retrans_collapse
--------------------
--
Jorge Nerin
<[email protected]>
--- old/proc.txt Mon Oct 23 15:20:00 2000
+++ new/proc.txt Mon Nov 13 00:20:24 2000
@@ -46,7 +46,7 @@
the SuSE Linux distribution. As there is no complete documentation for the
/proc file system and we've used many freely available sources to write these
chapters, it seems only fair to give the work back to the Linux community.
-This work is based on the 2.2.* kernel version. I'm afraid it's still far from
+This work is based on the 2.2.* kernel version and the upcomming 2.4.*. I'm afraid it's still far from
complete, but we hope it will be useful. As far as we know, it is the first
'all-in-one' document about the /proc file system. It is focused on the Intel
x86 hardware, so if you are looking for PPC, ARM, SPARC, APX, etc., features,
@@ -92,7 +92,7 @@
The proc file system acts as an interface to internal data structures in the
kernel. It can be used to obtain information about the system and to change
-certain kernel parameters at runtime.
+certain kernel parameters at runtime (sysctl).
First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
show you how you can use /proc/sys to change settings.
@@ -111,16 +111,17 @@
..............................................................................
File Content
cmdline Command line arguments
- environ Values of environment variables
+ cpu Current and last cpu in wich it was executed (2.4)(smp)
+ cwd Link to the Current Working Directory
+ environ Values of environment variables
+ exe Link to the executable in the filesystem
fd Directory, which contains all file descriptors
+ maps Maps to executables and library files (2.4)
mem Memory held by this process
+ root Link to the root directory of this process
stat Process status
- status Process status in human readable form
- cwd Link to the current working directory
- exe Link to the executable of this process
- maps Memory maps
- root Link to the root directory of this process
statm Process memory status information
+ status Process status in human readable form
..............................................................................
For example, to get the status information of a process, all you have to do is
@@ -131,6 +132,7 @@
State: R (running)
Pid: 5452
PPid: 743
+ TracerPid: 0 (2.4)
Uid: 501 501 501 501
Gid: 100 100 100 100
Groups: 100 14 16
@@ -187,13 +189,20 @@
devices Available devices (block and character)
dma Used DMS channels
filesystems Supported filesystems
+ driver Various drivers grouped here, currently rtc (2.4)
+ execdomains Execdomains, related to security (2.4)
+ fb Frame Buffer devices (2.4)
+ fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
interrupts Interrupt usage
+ iomem Memory map (2.4)
ioports I/O port usage
- kcore Kernel core image (can be ELF or A.OUT)
+ irq Masks for irq to cpu affinity (2.4)(smp?)
+ isapnp ISA PnP (Plug&Play) Info (2.4)
+ kcore Kernel core image (can be ELF or A.OUT(depreciated in 2.4))
kmsg Kernel messages
ksyms Kernel symbol table
- loadavg Load average
+ loadavg Load average of last 1, 5 & 15 minutes
locks Kernel locks
meminfo Memory info
misc Miscellaneous
@@ -201,14 +210,19 @@
mounts Mounted filesystems
net Networking info (see text)
partitions Table of partitions known to the system
+ pci Depreciated info of PCI bus (new way -> /proc/bus/pci/,
+ decoupled by lspci (2.4)
rtc Real time clock
scsi SCSI info (see text)
slabinfo Slab pool info
stat Overall statistics
swaps Swap space utilization
sys See chapter 2
+ sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
+ tty Info of tty drivers
uptime System uptime
version Kernel version
+ video bttv info of video resources (2.4)
..............................................................................
You can, for example, check which interrupts are currently in use and what
@@ -230,6 +244,68 @@
15: 7 XT-PIC ide1
NMI: 0
+In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
+output of a SMP machine):
+
+ > cat /proc/interrupts
+
+ CPU0 CPU1
+ 0: 1243498 1214548 IO-APIC-edge timer
+ 1: 8949 8958 IO-APIC-edge keyboard
+ 2: 0 0 XT-PIC cascade
+ 5: 11286 10161 IO-APIC-edge soundblaster
+ 8: 1 0 IO-APIC-edge rtc
+ 9: 27422 27407 IO-APIC-edge 3c503
+ 12: 113645 113873 IO-APIC-edge PS/2 Mouse
+ 13: 0 0 XT-PIC fpu
+ 14: 22491 24012 IO-APIC-edge ide0
+ 15: 2183 2415 IO-APIC-edge ide1
+ 17: 30564 30414 IO-APIC-level eth0
+ 18: 177 164 IO-APIC-level bttv
+ NMI: 2457961 2457959
+ LOC: 2457882 2457881
+ ERR: 2155
+
+NMI is incremented in this case because every timer interrupt generates a NMI
+(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lookups.
+
+LOC is the local interrupt counter of the internal APIC of every CPU.
+
+ERR is incremented in the case of errors in the IO-APIC bus (the bus that
+connects the CPUs in a SMP system. This means that an error has been detected,
+the IO-APIC automatically retry the transmision, so it should not be a big
+problem, but you should read the SMP-FAQ.
+
+In this context it could be interesting to note the new irq directory in 2.4.
+It could be used to set IRQ to CPU affinity, this means that you can "hook" an
+IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
+irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask
+
+For example
+ > ls /proc/irq/
+ 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
+ 1 11 13 15 17 19 3 5 7 9
+ > ls /proc/irq/0/
+ smp_affinity
+
+The contents of the prof_cpu_mask file and each smp_affinity file for each IRQ
+is the same by default:
+
+ > cat /proc/irq/0/smp_affinity
+ ffffffff
+
+It's a bitmask, in wich you can specify wich CPUs can handle the IRQ, you can
+set it by doing:
+
+ > echo 1 > /proc/irq/prof_cpu_mask
+
+This means that only the first CPU will handle the IRQ, but you can also echo 5
+wich means that only the first and fourth CPU can handle the IRQ.
+
+The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
+between all the CPUs which are allowed to handle it. As usual the kernel has
+more info than you and does a better job than you, so the defaults are the
+best choice for almost everyone.
There are three more important subdirectories in /proc: net, scsi, and sys.
The general rule is that the contents, or even the existence of these
@@ -1306,6 +1382,15 @@
TCP settings
------------
+
+tcp_ecn
+-------
+
+This file controls the use of the ECN bit in the IPv4 headers, this is a new
+feature about Explicit Congestion Notification, but some routers and firewalls
+block trafic that has this bit set, so it could be necessary to echo 0 to
+/proc/sys/net/ipv4/tcp_ecn, if you want to talk to this sites. For more info
+you could read RFC2481.
tcp_retrans_collapse
--------------------
Jorge Nerin wrote:
>
> Jorge Nerin wrote:
> >
> > Hello, this is a patch with some updates to the Documetation/proc.txt
> > file, basically it contains updates to the new files in /proc/<PID>, new
> > files in /proc, and a paragraph about /proc/sys/net/ipv4/tcp_ecn. It's
> > far from complete, but it's a start point.
> >
>
> Well, netscape seems to wrap long lines, as Peter Samuelson noticed me,
> so I send it again as an attachment.
>
> --
> Jorge Nerin
> <[email protected]>
Another little update to the patch, this time with bits from Philipp
Matthias Hahn, and a little formating change to break a very long line
in the middle of a paragraph.
--
Jorge Nerin
<[email protected]>
Jorge Nerin wrote:
>
> Jorge Nerin wrote:
> >
> > Jorge Nerin wrote:
> > >
> > > Hello, this is a patch with some updates to the Documetation/proc.txt
> > > file, basically it contains updates to the new files in /proc/<PID>, new
> > > files in /proc, and a paragraph about /proc/sys/net/ipv4/tcp_ecn. It's
> > > far from complete, but it's a start point.
> > >
> >
> > Well, netscape seems to wrap long lines, as Peter Samuelson noticed me,
> > so I send it again as an attachment.
> >
> > --
> > Jorge Nerin
> > <[email protected]>
>
> Another little update to the patch, this time with bits from Philipp
> Matthias Hahn, and a little formating change to break a very long line
> in the middle of a paragraph.
>
> --
> Jorge Nerin
> <[email protected]>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> Please read the FAQ at http://www.tux.org/lkml/
I have to be more careful, I don't know if I forgot to attach the file or
if the majordomo has dropped it?, probably the first one.
So again, the update:
(let's hope it doesn't wrap)
--- old/proc.txt Mon Oct 23 15:20:00 2000
+++ new/proc.txt Wed Nov 15 00:04:48 2000
@@ -3,8 +3,11 @@
------------------------------------------------------------------------------
/proc/sys Terrehon Bowden <[email protected]> October 7 1999
Bodo Bauer <[email protected]>
+
+2.4.x update Jorge Nerin <[email protected]> November 14 2000
------------------------------------------------------------------------------
-Version 1.2 Kernel version 2.2.12
+Version 1.3 Kernel version 2.2.12
+ Kernel version 2.4.0-test11-pre4
------------------------------------------------------------------------------
Table of Contents
@@ -42,17 +45,18 @@
0.1 Introduction/Credits
------------------------
-This documentation is part of a soon (or so we hope) to be released book on
-the SuSE Linux distribution. As there is no complete documentation for the
-/proc file system and we've used many freely available sources to write these
-chapters, it seems only fair to give the work back to the Linux community.
-This work is based on the 2.2.* kernel version. I'm afraid it's still far from
-complete, but we hope it will be useful. As far as we know, it is the first
-'all-in-one' document about the /proc file system. It is focused on the Intel
-x86 hardware, so if you are looking for PPC, ARM, SPARC, APX, etc., features,
-you probably won't find what you are looking for. It also only covers IPv4
-networking, not IPv6 nor other protocols - sorry. But additions and patches
-are welcome and will be added to this document if you mail them to Bodo.
+This documentation is part of a soon (or so we hope) to be released book on
+the SuSE Linux distribution. As there is no complete documentation for the
+/proc file system and we've used many freely available sources to write these
+chapters, it seems only fair to give the work back to the Linux community.
+This work is based on the 2.2.* kernel version and the upcomming 2.4.*. I'm
+afraid it's still far from complete, but we hope it will be useful. As far as
+we know, it is the first 'all-in-one' document about the /proc file system. It
+is focused on the Intel x86 hardware, so if you are looking for PPC, ARM,
+SPARC, APX, etc., features, you probably won't find what you are looking for.
+It also only covers IPv4 networking, not IPv6 nor other protocols - sorry. But
+additions and patches are welcome and will be added to this document if you
+mail them to Bodo.
We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
other people for help compiling this documentation. We'd also like to extend a
@@ -65,9 +69,13 @@
contact Bodo Bauer at [email protected]. We'll be happy to add them to this
document.
-The latest version of this document is available online at
+The latest version of this document is available online at
http://skaro.nightcrawler.com/~bb/Docs/Proc as HTML version.
+If the above direction does not works for you, ypu could try the kernel
+mailing list at [email protected] and/or try to reach me at
[email protected].
+
0.2 Legal Stuff
---------------
@@ -92,7 +100,7 @@
The proc file system acts as an interface to internal data structures in the
kernel. It can be used to obtain information about the system and to change
-certain kernel parameters at runtime.
+certain kernel parameters at runtime (sysctl).
First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
show you how you can use /proc/sys to change settings.
@@ -111,16 +119,17 @@
..............................................................................
File Content
cmdline Command line arguments
- environ Values of environment variables
+ cpu Current and last cpu in wich it was executed (2.4)(smp)
+ cwd Link to the current working directory
+ environ Values of environment variables
+ exe Link to the executable of this process
fd Directory, which contains all file descriptors
+ maps Memory maps to executables and library files (2.4)
mem Memory held by this process
+ root Link to the root directory of this process
stat Process status
- status Process status in human readable form
- cwd Link to the current working directory
- exe Link to the executable of this process
- maps Memory maps
- root Link to the root directory of this process
statm Process memory status information
+ status Process status in human readable form
..............................................................................
For example, to get the status information of a process, all you have to do is
@@ -131,6 +140,7 @@
State: R (running)
Pid: 5452
PPid: 743
+ TracerPid: 0 (2.4)
Uid: 501 501 501 501
Gid: 100 100 100 100
Groups: 100 14 16
@@ -187,13 +197,20 @@
devices Available devices (block and character)
dma Used DMS channels
filesystems Supported filesystems
+ driver Various drivers grouped here, currently rtc (2.4)
+ execdomains Execdomains, related to security (2.4)
+ fb Frame Buffer devices (2.4)
+ fs File system parameters, currently nfs/exports (2.4)
ide Directory containing info about the IDE subsystem
interrupts Interrupt usage
+ iomem Memory map (2.4)
ioports I/O port usage
- kcore Kernel core image (can be ELF or A.OUT)
+ irq Masks for irq to cpu affinity (2.4)(smp?)
+ isapnp ISA PnP (Plug&Play) Info (2.4)
+ kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
kmsg Kernel messages
ksyms Kernel symbol table
- loadavg Load average
+ loadavg Load average of last 1, 5 & 15 minutes
locks Kernel locks
meminfo Memory info
misc Miscellaneous
@@ -201,14 +218,19 @@
mounts Mounted filesystems
net Networking info (see text)
partitions Table of partitions known to the system
+ pci Depreciated info of PCI bus (new way -> /proc/bus/pci/,
+ decoupled by lspci (2.4)
rtc Real time clock
scsi SCSI info (see text)
slabinfo Slab pool info
stat Overall statistics
swaps Swap space utilization
sys See chapter 2
+ sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
+ tty Info of tty drivers
uptime System uptime
version Kernel version
+ video bttv info of video resources (2.4)
..............................................................................
You can, for example, check which interrupts are currently in use and what
@@ -230,6 +252,68 @@
15: 7 XT-PIC ide1
NMI: 0
+In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
+output of a SMP machine):
+
+ > cat /proc/interrupts
+
+ CPU0 CPU1
+ 0: 1243498 1214548 IO-APIC-edge timer
+ 1: 8949 8958 IO-APIC-edge keyboard
+ 2: 0 0 XT-PIC cascade
+ 5: 11286 10161 IO-APIC-edge soundblaster
+ 8: 1 0 IO-APIC-edge rtc
+ 9: 27422 27407 IO-APIC-edge 3c503
+ 12: 113645 113873 IO-APIC-edge PS/2 Mouse
+ 13: 0 0 XT-PIC fpu
+ 14: 22491 24012 IO-APIC-edge ide0
+ 15: 2183 2415 IO-APIC-edge ide1
+ 17: 30564 30414 IO-APIC-level eth0
+ 18: 177 164 IO-APIC-level bttv
+ NMI: 2457961 2457959
+ LOC: 2457882 2457881
+ ERR: 2155
+
+NMI is incremented in this case because every timer interrupt generates a NMI
+(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lookups.
+
+LOC is the local interrupt counter of the internal APIC of every CPU.
+
+ERR is incremented in the case of errors in the IO-APIC bus (the bus that
+connects the CPUs in a SMP system. This means that an error has been detected,
+the IO-APIC automatically retry the transmision, so it should not be a big
+problem, but you should read the SMP-FAQ.
+
+In this context it could be interesting to note the new irq directory in 2.4.
+It could be used to set IRQ to CPU affinity, this means that you can "hook" an
+IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
+irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask
+
+For example
+ > ls /proc/irq/
+ 0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
+ 1 11 13 15 17 19 3 5 7 9
+ > ls /proc/irq/0/
+ smp_affinity
+
+The contents of the prof_cpu_mask file and each smp_affinity file for each IRQ
+is the same by default:
+
+ > cat /proc/irq/0/smp_affinity
+ ffffffff
+
+It's a bitmask, in wich you can specify wich CPUs can handle the IRQ, you can
+set it by doing:
+
+ > echo 1 > /proc/irq/prof_cpu_mask
+
+This means that only the first CPU will handle the IRQ, but you can also echo 5
+wich means that only the first and fourth CPU can handle the IRQ.
+
+The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
+between all the CPUs which are allowed to handle it. As usual the kernel has
+more info than you and does a better job than you, so the defaults are the
+best choice for almost everyone.
There are three more important subdirectories in /proc: net, scsi, and sys.
The general rule is that the contents, or even the existence of these
@@ -1306,6 +1390,15 @@
TCP settings
------------
+
+tcp_ecn
+-------
+
+This file controls the use of the ECN bit in the IPv4 headers, this is a new
+feature about Explicit Congestion Notification, but some routers and firewalls
+block trafic that has this bit set, so it could be necessary to echo 0 to
+/proc/sys/net/ipv4/tcp_ecn, if you want to talk to this sites. For more info
+you could read RFC2481.
tcp_retrans_collapse
--------------------
--
Jorge Nerin
<[email protected]>