linux-kernel - Re: [PATCH v2 1/4] tracing/histogram: Optimize division by constants

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Message-ID: <20211029162549.2c22f2dd@gandalf.local.home>
Date:   Fri, 29 Oct 2021 16:25:49 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Kalesh Singh <kaleshsingh@...gle.com>
Cc:     surenb@...gle.com, hridya@...gle.com, namhyung@...nel.org,
        kernel-team@...roid.com, mhiramat@...nel.org,
        Jonathan Corbet <corbet@....net>,
        Ingo Molnar <mingo@...hat.com>, Shuah Khan <shuah@...nel.org>,
        Tom Zanussi <zanussi@...nel.org>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v2 1/4] tracing/histogram: Optimize division by
 constants

On Fri, 29 Oct 2021 11:53:16 -0700
Kalesh Singh <kaleshsingh@...gle.com> wrote:

> > If these functions are only called when val2 is constant, can't we make it
> > such that we get val2 from the hist_field directly? That is:
> >
> >         u64 val2 = operand2->constant;  
> 
> operand2 might be a var ref to a constant, so we would need to resolve
> that with hist_field_var_ref().

So can a var_ref change? If not, then we should convert that to a constant
for this operation.

-- Steve