On 15-Jun-20 12:43 PM, Jerin Jacob wrote:
On Mon, Jun 15, 2020 at 5:02 PM Burakov, Anatoly
<anatoly.bura...@intel.com> wrote:
On 02-Jun-20 1:16 PM, Harman Kalra wrote:
On Tue, Jun 02, 2020 at 03:53:07PM +0530, Harman Kalra wrote:
On Mon, Jun 01, 2020 at 01:50:26PM +0100, Burakov, Anatoly wrote:
On 30-May-20 11:02 AM, Harman Kalra wrote:
On Fri, May 29, 2020 at 03:19:45PM +0100, Burakov, Anatoly wrote:
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On 29-May-20 2:19 PM, Harman Kalra wrote:
if (ret < 0)
rte_exit(EXIT_FAILURE, "Invalid L3FWD parameters\n");
- if (app_mode != APP_MODE_TELEMETRY && init_power_library())
+ if (app_mode == APP_MODE_DEFAULT)
+ app_mode = APP_MODE_LEGACY;
+
+ /* only legacy and empty poll mode rely on power library */
+ if ((app_mode == APP_MODE_LEGACY || app_mode == APP_MODE_EMPTY_POLL) &&
+ init_power_library())
rte_exit(EXIT_FAILURE, "init_power_library failed\n");
Hi,
Rather than just exiting from here can we have a else condition to
automatically enter into the "interrupt only" mode.
Please correct me if I am missing something.
Hi,
Thanks for your review. I don't think silently proceeding is a good idea. If
the user wants interrupt-only mode, they should request it. Silently falling
back to interrupt-only mode will create an illusion of successful
initialization and set the wrong expectation for how the application will
behave.
Hi,
Thanks for the explanation which even I also believe is logically perfect.
But since l3fwd-power is an old application and has many users around
which are currently using this app in interrupt only mode without giving
an extra argument. But suddenly they will start getting failure messages with
the new patchset.
My only intent with else condition was backward compatibility.
Or may be we can have more descriptive failure message, something like
"init_power_library failed, check manual for other modes".
Thanks
Harman
I think we can compormise on an informative log message suggesting to use
interrupt mode. I'm not keen on reverting to previous buggy behavior :)
Hi
I am not insisting to revert to previous behavior, I am just trying to
highlight some probable issues that many users might face as its an old
application.
Since many arm based soc might not be supporting frequency scaling, can
we add the following check as soon as the application starts, probe the
platform if it supports frequency scaling, if not automatically set the
mode to interrupt mode, something like:
if (access("/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",
F_OK))
app_mode = APP_MODE_INTERRUPT;
Sorry, no direct check in application but we can introduce a new API in
power library:
bool rte_is_freq_scaling() {
return
access("/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",
F_OK);
}
and in the application we can use "rte_is_freq_scaling()" at the start.
What you're suggesting here is effectively what you have already
suggested: silently fall back to interrupt-only mode if power lib init
failed. I already outlined why i don't think it's a good approach.
Is probing "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"
file presence,
detects the power lib availability . Right? Not the failure. Right?
IMO, it make sense to have following case:
# first check, Is the system is capable of power lib if so use power lib
# if the system is not capable of using power lib use interrupt mode.
I think, there is difference between system capable of using power lib
vs power lib not available or power lib failure.
I am of the opinion that if a test sets up an unrealistic expectation of
how an application should behave, it's a problem with the test, not with
the application.
If the system is not capable of running with power lib - the application
shouldn't be requested to run in such mode.
"The application behaved that way before" - yes, it did. It was a bug in
the application, that it allowed users to effectively misuse the
application and use it despite the fact that it was in a half-working
state. This problem has been addressed by 1) not allowing the
application to run in half-working state, and 2) adding a new mode where
the old "expected" behavior is *actually* expected and is "full working
state" now.
Therefore, all users who were previously misusing the application to do
something it was not designed to do because of a bug in the
implementation, should now fix their usage and use the correct mode -
and such breakage is IMO necessary to call attention to earlier misuse
in the tools, and to correct this usage.
What bothers me about your suggestion is that it is impossible to fail
the test if the wrong mode was requested (as in, if we request the
power-lib mode on a system that doesn't have freq scaling) - it instead
silently falls back to a mode that is almost guaranteed to work.
--
Thanks,
Anatoly
