Hi Yuriy,
I am using util-linux v2.27 and GLIBC v2.21 on ubuntu.
As you pointed out rightly, its the invalid logical cpu number, rather
than mis-parsed argument. I was confused because of the error message.
Thanks :)
On Sun, Feb 28, 2016 at 5:53 AM, Yuriy M. Kaminskiy <yumkam@xxxxxxxxx> wrote:
> yumkam@xxxxxxxxx (Yuriy M. Kaminskiy)
> writes:
>
>> Akshay Adiga <akshay.adiga@xxxxxxxxx>
>> writes:
>>
>>> I want to run a command which looks something like this :
>>>
>>> taskset -c 10 ycsb -p "redis_host=1234"
>>>
>>> The actual command is :
>>>
>>> ycsb -p "redis_host=1234"
>>>
>>> But argument -p "redis_host=1234" is taken by taskset as it argument
>>> and throws an error : Failed to set pid 0's affinity:
>>>
>>> -p "redis_host=1234" is an argument to ycsb command. shell/tasket
>>> misunderstands that and takes it as an argument for taskset.
>>>
>>> Is there a work around for this?
>>
>> Normally, such problem are solved by inserting `--` before your command;
>> however, taskset have somewhat unusual parsing of arguments (-c is not
>> an "option with argument", but the flag), so it will be
>>
>> taskset -c -- 10 ycsb -p "redis_host=1234"
>
> Hmm... actually, on which util-linux and libc version this is on?
>
> This should work even without -- (and it works for me [on util-linux 2.25.2
> and glibc 2.19; and on util-linux git master branch too), note `getopt
> ... "+` in taskset.c and `man 3 getopt_long` on meaning (getopt should
> stop parsing on first non-option argument, in your case `ycsb`).
>
> And do your system have 10 cpu's/cores/whatever? Because if I specify cpu number
> larger than present, taskset gives exactly this error:
>
> $ taskset -c 100 echo -p foobar
> taskset: failed to set pid 0's affinity: Invalid argument
>
> This may be confused as "incorrect argument parsing", but it is not
> ("pid 0" is just means it tries to apply affinity to itself, it is not
> misparsed "foobar"); with existing cpu number everything works:
>
> $ taskset -c 1 echo -p foobar
> -p foobar
> $ taskset -c -- 1 echo -p foobar
> -p foobar
>
> (That said, taskset and chrt argument parsing is a bit unusual and may be confusing)
>
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