2000-10-28 13:04:41

by Vasil Kolev

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Subject: PLIP driver in 2.2.xx kernels

I have a question - Why does the PLIP driver does consume so much CPU ?
I tried it today, and when i did ping -s 16000 dst_ip, the kernel consumed
about 50% of the CPU time ( /proc/cpuinfo and /proc/interrupts follow).
Any ideas ?

shtajga:~# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 7
model name : Pentium III (Katmai)
stepping : 3
cpu MHz : 548.545
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
sep_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 3
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov
pat pse36 psn mmx fxsr xmm
bogomips : 1094.45
shtajga:~# cat /proc/interrupts
CPU0
0: 32765032 XT-PIC timer
1: 227971 XT-PIC keyboard
2: 0 XT-PIC cascade
3: 42658190 XT-PIC serial
4: 518726307 XT-PIC serial
7: 45966 XT-PIC parport0
8: 1 XT-PIC rtc
9: 15292 XT-PIC eth0
10: 21984776 XT-PIC eth1
11: 1534661 XT-PIC sm200
12: 498413 XT-PIC PS/2 Mouse
13: 1 XT-PIC fpu
14: 18221483 XT-PIC ide0
15: 8 XT-PIC ide1
NMI: 0



2000-10-28 14:29:13

by Alan Cox

[permalink] [raw]
Subject: Re: PLIP driver in 2.2.xx kernels

> I have a question - Why does the PLIP driver does consume so much CPU ?
> I tried it today, and when i did ping -s 16000 dst_ip, the kernel consumed
> about 50% of the CPU time ( /proc/cpuinfo and /proc/interrupts follow).
> Any ideas ?

It has to bang on the parallel port controller the hard way, there is no
useful hardware support on a basic parallel port for the kind of abuse needed
for PLIP

2000-10-30 13:42:22

by Vasil Kolev

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Subject: Re: PLIP driver in 2.2.xx kernels



On Sat, 28 Oct 2000, Alan Cox wrote:

> > I have a question - Why does the PLIP driver does consume so much CPU ?
> > I tried it today, and when i did ping -s 16000 dst_ip, the kernel consumed
> > about 50% of the CPU time ( /proc/cpuinfo and /proc/interrupts follow).
> > Any ideas ?
>
> It has to bang on the parallel port controller the hard way, there is no
> useful hardware support on a basic parallel port for the kind of abuse needed
> for PLIP
>
(sorry for the late reply)
I used plip with kernel 1.2.8 and had no problem with it...The machines
that I'm using now are far superior than the old ones... Why shouldn't it
work now ?

2000-10-30 14:02:45

by Alan Cox

[permalink] [raw]
Subject: Re: PLIP driver in 2.2.xx kernels

> > It has to bang on the parallel port controller the hard way, there is no
> > useful hardware support on a basic parallel port for the kind of abuse needed
> > for PLIP
> >
> (sorry for the late reply)
> I used plip with kernel 1.2.8 and had no problem with it...The machines
> that I'm using now are far superior than the old ones... Why shouldn't it
> work now ?

The performance hasnt changed. Your fast CPU simply spends longer in a tight
loop between each thing it has to do. There are no interrupts we can use for
the nibble by nibble data sending