From: Jan Beulich <jbeulich@suse.com>
To: Jason Andryuk <jandryuk@gmail.com>
Cc: Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH 12/13] xenpm: Add set-cpufreq-hwp subcommand
Date: Thu, 27 May 2021 11:46:19 +0200 [thread overview]
Message-ID: <641bb656-ab47-5125-3660-fb9aa342800c@suse.com> (raw)
In-Reply-To: <20210503192810.36084-13-jandryuk@gmail.com>
On 03.05.2021 21:28, Jason Andryuk wrote:
> @@ -1309,6 +1328,226 @@ void disable_turbo_mode(int argc, char *argv[])
> errno, strerror(errno));
> }
>
> +/*
> + * Parse activity_window:NNN{us,ms,s} and validate range.
> + *
> + * Activity window is a 7bit mantissa (0-127) with a 3bit exponent (0-7) base
> + * 10 in microseconds. So the range is 1 microsecond to 1270 seconds. A value
> + * of 0 lets the hardware autonomously select the window.
> + *
> + * Return 0 on success
> + * -1 on error
> + * 1 Not activity_window. i.e. try parsing as another argument
> + */
> +static int parse_activity_window(xc_set_hwp_para_t *set_hwp, char *p)
> +{
> + char *param = NULL, *val = NULL, *suffix = NULL;
> + unsigned int u;
> + unsigned int exponent = 0;
> + unsigned int multiplier = 1;
> + int ret;
> +
> + ret = sscanf(p, "%m[a-z_A-Z]:%ms", ¶m, &val);
I have to confess that I first needed to look up availability of the
m modifier. It looks to be in POSIX.1-2008, but not in C11 and older.
I'm therefore not sure if you can legitimately use it; I've not been
able to spot pre-existing uses throughout tools/.
Also, following the naming of other options of this tool (including
the new set-cpufreq-hwp subcommand you add here), instead of _
options should use - (and the pattern here and in the other similar
sscanf() further down then wants adjusting).
> + if ( ret != 2 )
> + {
> + return -1;
No error message at all in this case?
> + }
> +
> + if ( strncasecmp(param, "act", 3) != 0 )
> + {
> + ret = 1;
> +
> + goto out;
> + }
> +
> + free(param);
> + param = NULL;
> +
> + ret = sscanf(val, "%u%ms", &u, &suffix);
Can't you parse this right in the first sscanf()?
> + if ( ret != 1 && ret != 2 )
> + {
> + fprintf(stderr, "invalid activity window: %s\n", val);
> +
> + ret = -1;
> +
> + goto out;
> + }
> +
> + if ( ret == 2 && suffix )
The help text doesn't clarify what an omitted suffix means; it's
unambiguous only when the value is zero. (While looking at that I
also started wondering whether the range there starting at 0us is
actually appropriate - the range really starts at 1us afaict, with
0 having special meaning.)
> + {
> + if ( strcasecmp(suffix, "s") == 0 )
> + {
> + multiplier = 1000 * 1000;
> + exponent = 6;
> + }
> + else if ( strcasecmp(suffix, "ms") == 0 )
> + {
> + multiplier = 1000;
> + exponent = 3;
> + }
> + else if ( strcasecmp(suffix, "us") == 0 )
> + {
> + multiplier = 1;
> + exponent = 0;
> + }
> + else
> + {
> + fprintf(stderr, "invalid activity window units: %s\n", suffix);
I think you want to generally quote %s in such cases, to make clear
what is actually part of a malformed string.
> + ret = -1;
> + goto out;
> + }
> + }
> +
> + if ( u > 1270 * 1000 * 1000 / multiplier )
> + {
> + fprintf(stderr, "activity window %s too large\n", val);
> +
> + ret = -1;
> + goto out;
> + }
> +
> + /* looking for 7 bits of mantissa and 3 bits of exponent */
> + while ( u > 127 )
Prior to this loop, don't you need to multiply by "multiplier"?
> + {
> + u /= 10;
Fractions get silently chopped off - may want spelling out in
the help text.
> + exponent += 1;
> + }
> +
> + set_hwp->activity_window = ( exponent & 0x7 ) << 7 | ( u & 0x7f );
Excess blanks inside parentheses again.
> +static int parse_hwp_opts(xc_set_hwp_para_t *set_hwp, int *cpuid,
> + int argc, char *argv[])
> +{
> + int i = 0;
> +
> + if ( argc < 1 )
> + return -1;
> +
> + if ( parse_cpuid_non_fatal(argv[i], cpuid) == 0 )
> + {
> + i++;
> + }
Unnecessary braces again, the more that you ...
> + if ( i == argc )
> + return -1;
... don't have any here.
> + if ( strcasecmp(argv[i], "powersave") == 0 )
> + {
> + set_hwp->set_params = XEN_SYSCTL_HWP_SET_PRESET_POWERSAVE;
> + i++;
> + }
> + else if ( strcasecmp(argv[i], "performance") == 0 )
> + {
> + set_hwp->set_params = XEN_SYSCTL_HWP_SET_PRESET_PERFORMANCE;
> + i++;
> + }
> + else if ( strcasecmp(argv[i], "balance") == 0 )
> + {
> + set_hwp->set_params = XEN_SYSCTL_HWP_SET_PRESET_BALANCE;
> + i++;
> + }
> +
> + for ( ; i < argc; i++)
> + {
> + unsigned int val;
> + char *param;
> + int ret;
> +
> + ret = parse_activity_window(set_hwp, argv[i]);
> + switch ( ret )
> + {
> + case -1:
> + return -1;
> + case 0:
> + continue;
> + break;
Why "break" after "continue"? I can see compilers legitimately warning
in such a case.
> + case 1:
This may better be "default:", or could be omitted altogether. Or
alternatively you may want to have a "default:" with assert().
> + /* try other parsing */
> + break;
> + }
> +
> + /* sscanf can't handle split on ':' for "%ms:%u' */
> + ret = sscanf(argv[i], "%m[a-zA-Z_]:%u", ¶m, &val);
> + if ( ret != 2 )
> + {
> + fprintf(stderr, "%s is an invalid hwp parameter.\n", argv[i]);
Outside of this function you omit full stops from error messages.
Elsewhere in the tool full stops are also absent except in two or
three deprecation warnings. Hence I think you want to drop them
from messages in this function.
> + return -1;
> + }
> +
> + if ( val > 255 )
> + {
> + fprintf(stderr, "%s value %u is out of range.\n", param, val);
> + return -1;
> + }
> +
> + if ( strncasecmp(param, "min", 3) == 0 )
> + {
> + set_hwp->minimum = val;
> + set_hwp->set_params |= XEN_SYSCTL_HWP_SET_MINIMUM;
> + }
> + else if ( strncasecmp(param, "max", 3) == 0 )
> + {
> + set_hwp->maximum = val;
> + set_hwp->set_params |= XEN_SYSCTL_HWP_SET_MAXIMUM;
> + }
> + else if ( strncasecmp(param, "des", 3) == 0 )
> + {
> + set_hwp->desired = val;
> + set_hwp->set_params |= XEN_SYSCTL_HWP_SET_DESIRED;
> + }
> + else if ( strncasecmp(param, "ene", 3) == 0 )
> + {
> + set_hwp->energy_perf = val;
> + set_hwp->set_params |= XEN_SYSCTL_HWP_SET_ENERGY_PERF;
> + }
While I can see the point of limiting to 3 characters, you would
better not accept longer but e.g. typoed strings.
> + else
> + {
> + fprintf(stderr, "%s is an invalid parameter\n.", param);
> + return -1;
> + }
> +
> + free(param);
> + }
> +
> + return 0;
Should you perhaps return an error here if set_hwp->set_params is
still zero?
> +}
> +
> +static void hwp_set_func(int argc, char *argv[])
> +{
> + xc_set_hwp_para_t set_hwp = {};
> + int cpuid = -1;
> + int i = 0;
> +
> + if ( parse_hwp_opts(&set_hwp, &cpuid, argc, argv) )
> + {
> + fprintf(stderr, "Missing, excess, or invalid argument(s)\n");
Isn't this redundant with earlier logged messages, which are also
more specific (with the one exception noted)?
Jan
next prev parent reply other threads:[~2021-05-27 9:46 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-03 19:27 [PATCH 00/13] Intel Hardware P-States (HWP) support Jason Andryuk
2021-05-03 19:27 ` [PATCH 01/13] cpufreq: Allow restricting to internal governors only Jason Andryuk
2021-05-26 13:18 ` Jan Beulich
2021-05-26 14:12 ` Jason Andryuk
2021-05-26 15:09 ` Jan Beulich
2021-05-26 16:44 ` Jason Andryuk
2021-05-03 19:27 ` [PATCH 02/13] cpufreq: Add perf_freq to cpuinfo Jason Andryuk
2021-05-26 13:24 ` Jan Beulich
2021-05-26 14:19 ` Jason Andryuk
2021-05-03 19:28 ` [PATCH 03/13] cpufreq: Export intel_feature_detect Jason Andryuk
2021-05-26 13:27 ` Jan Beulich
2021-05-26 14:44 ` Jason Andryuk
2021-05-26 15:11 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 04/13] cpufreq: Add Hardware P-State (HWP) driver Jason Andryuk
2021-05-26 14:59 ` Jan Beulich
2021-05-27 7:23 ` Jan Beulich
2021-05-27 18:50 ` Jason Andryuk
2021-05-28 6:35 ` Jan Beulich
2021-06-03 11:55 ` Jason Andryuk
2021-06-04 6:39 ` Jan Beulich
2021-05-27 7:45 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 05/13] xenpm: Change get-cpufreq-para output for internal Jason Andryuk
2021-05-26 15:21 ` Jan Beulich
2021-05-27 5:54 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 06/13] cpufreq: Export HWP parameters to userspace Jason Andryuk
2021-05-27 7:55 ` Jan Beulich
2021-05-28 13:19 ` Jason Andryuk
2021-05-28 13:39 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 07/13] libxc: Include hwp_para in definitions Jason Andryuk
2021-05-03 19:28 ` [PATCH 08/13] xenpm: Print HWP parameters Jason Andryuk
2021-05-27 8:02 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 09/13] xen: Add SET_CPUFREQ_HWP xen_sysctl_pm_op Jason Andryuk
2021-05-27 8:33 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 10/13] libxc: Add xc_set_cpufreq_hwp Jason Andryuk
2021-05-04 8:03 ` Jan Beulich
2021-05-04 11:31 ` Jason Andryuk
2021-05-27 9:45 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 11/13] xenpm: Factor out a non-fatal cpuid_parse variant Jason Andryuk
2021-05-27 8:41 ` Jan Beulich
2021-05-03 19:28 ` [PATCH 12/13] xenpm: Add set-cpufreq-hwp subcommand Jason Andryuk
2021-05-27 9:46 ` Jan Beulich [this message]
2021-05-03 19:28 ` [PATCH 13/13] CHANGELOG: Add Intel HWP entry Jason Andryuk
2021-05-27 9:48 ` Jan Beulich
2021-05-20 14:57 ` [PATCH 00/13] Intel Hardware P-States (HWP) support Jan Beulich
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