looking for something like raw_rwlock_t in Linux 3.0

[Priyanka Gupta Jain <p.priyankagupta@gmail.com>]

hi,

I am still looking for the answer to the below. I will be highly
thankful if someone can help in it.

Is there something like raw_rwlock_t in Linux3.0 which can make the
rwlock_t behave in similar way as in RT disable.
This might help me in solving throughput issue in 8-core system due to
read/write lock.

Regards
Priyanka

On Wed, Apr 11, 2012 at 10:32 AM, Priyanka Gupta Jain
<p.priyankagupta@gmail.com> wrote:
> hi,
>
> I am observing drastic throughput reduction in IPSEC traffic with RT
> enable and disable. Throughput drops from 576 fps to 69fps.
> Please note that I am using 8-core system with Linux 3.0.26-rt45 (SMP)
> running on it.
>
> With the help of ftrace (function graph) in case of RT enable, I could
> see xfrm_policy_get_afinfo() and xfrm_policy_put_afinfo taking time()
> sometimes taking time arounnd 1.43 msec and  1.351msec respectively.
>
> As in my test case, I was writing afinfo_policy before starting the
> traffic without chainging in between, it was safe to remove read lock
> and read unlock from xfrm_policy_get_afinfo() and
> xfrm_policy_put_afinfo() functions. With the read lock/unlock removed,
> I could see throughput rising from 69fps to 133fps.
>
> Now I need your suggestions for the below:
> 1) Removing the read lock is not a good way as the system might now
> work properly in the real set-up. But with the change of read-write
> lock to mutex by PREEMPT_RT patch, I am not able to fully utilize
> 8-core system leading to drastic reduction in throughput. So what is
> the suggested way to tackle this situation.
>
> 2) Even after removing the read lock, I could see the difference in
> IPSEC thoughput in RT enable (133fps) and RT disable (576fps). Any
> suggestion?.
>
>
> Regards
> Priyanka
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