linux-kernel - Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle

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Message-Id: <1580885398.01q0jv6qlp.naveen@linux.ibm.com>
Date:   Wed, 05 Feb 2020 12:28:49 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     ego@...ux.vnet.ibm.com
Cc:     Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Nathan Lynch <nathanl@...ux.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Tyrel Datwyler <tyreld@...ux.ibm.com>
Subject: Re: [PATCH 2/3] powerpc/sysfs: Show idle_purr and idle_spurr for
 every CPU

Gautham R Shenoy wrote:
> 
>> With repect to lparstat, the read interval is user-specified and just gets
>> passed onto sleep().
> 
> Ok. So I guess currently you will be sending smp_call_function every
> time you read a PURR and SPURR. That number will now increase by 2
> times when we read idle_purr and idle_spurr.

Yes, not really efficient. I just wanted to point out that we can't have 
stale data being returned if we choose to add another sysfs file.

We should be able to use any other interface too, if you have a 
different interface in mind.


- Naveen