[libvirt] [PATCH 3/6] util: Introduce virHostCPUGetInfoParseCPUFrequency()
Bjoern Walk
bwalk at linux.vnet.ibm.com
Wed Dec 13 07:42:47 UTC 2017
Andrea Bolognani <abologna at redhat.com> [2017-12-11, 05:40PM +0100]:
> The algorithm used to extract the CPU frequency from /proc/cpuinfo
> is the same regardless of architecture, the only difference being
> the label used to identify the relevant field.
>
> Factor the parsing code out to a new helper and use it to implement
> virHostCPUGetInfoParseCPUInfo(), thus removing some duplication.
>
> Signed-off-by: Andrea Bolognani <abologna at redhat.com>
> ---
> src/util/virhostcpu.c | 105 +++++++++++++++++++-------------------------------
> 1 file changed, 40 insertions(+), 65 deletions(-)
>
> diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
> index 4d5c56659..85803d527 100644
> --- a/src/util/virhostcpu.c
> +++ b/src/util/virhostcpu.c
> @@ -509,6 +509,40 @@ virHostCPUHasValidSubcoreConfiguration(int threads_per_subcore)
> }
>
>
> +static int
> +virHostCPUGetInfoParseCPUFrequency(const char *buf,
> + const char *label,
> + unsigned int *mhz)
> +{
> + int ret = -1;
> +
> + if (STRPREFIX(buf, label)) {
I'd prefer negation and early exit to get rid of one indentation level.
I also moved this conditional into the loop below. Save function calls.
> + char *p;
> + unsigned int ui;
> +
> + buf += strlen(label);
> + while (*buf && c_isspace(*buf))
> + buf++;
> +
> + if (*buf != ':' || !buf[1]) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("parsing cpu MHz from cpuinfo"));
> + goto cleanup;
> + }
> +
> + if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 &&
> + /* Accept trailing fractional part. */
> + (*p == '\0' || *p == '.' || c_isspace(*p)))
> + *mhz = ui;
> + }
> +
> + ret = 0;
> +
> + cleanup:
> + return ret;
> +}
> +
> +
> static int
> virHostCPUGetInfoParseCPUInfo(FILE *cpuinfo,
> virArch arch,
> @@ -521,73 +555,14 @@ virHostCPUGetInfoParseCPUInfo(FILE *cpuinfo,
>
> while (fgets(line, sizeof(line), cpuinfo) != NULL) {
> if (ARCH_IS_X86(arch)) {
Probably (hopefully?) the compiler can optimize, but I get a bit iffy if
I see a loop invariant conditional inside a loop. I find this also
harder to read.
> - char *buf = line;
> - if (STRPREFIX(buf, "cpu MHz")) {
> - char *p;
> - unsigned int ui;
> -
> - buf += 7;
> - while (*buf && c_isspace(*buf))
> - buf++;
> -
> - if (*buf != ':' || !buf[1]) {
> - virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> - _("parsing cpu MHz from cpuinfo"));
> - goto cleanup;
> - }
> -
> - if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 &&
> - /* Accept trailing fractional part. */
> - (*p == '\0' || *p == '.' || c_isspace(*p)))
> - *mhz = ui;
> - }
> + if (virHostCPUGetInfoParseCPUFrequency(line, "cpu MHz", mhz) < 0)
> + goto cleanup;
> } else if (ARCH_IS_PPC(arch)) {
> - char *buf = line;
> - if (STRPREFIX(buf, "clock")) {
> - char *p;
> - unsigned int ui;
> -
> - buf += 5;
> - while (*buf && c_isspace(*buf))
> - buf++;
> -
> - if (*buf != ':' || !buf[1]) {
> - virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> - _("parsing cpu MHz from cpuinfo"));
> - goto cleanup;
> - }
> -
> - if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 &&
> - /* Accept trailing fractional part. */
> - (*p == '\0' || *p == '.' || c_isspace(*p)))
> - *mhz = ui;
> - /* No other interesting infos are available in /proc/cpuinfo.
> - * However, there is a line identifying processor's version,
> - * identification and machine, but we don't want it to be caught
> - * and parsed in next iteration, because it is not in expected
> - * format and thus lead to error. */
> - }
> + if (virHostCPUGetInfoParseCPUFrequency(line, "clock", mhz) < 0)
> + goto cleanup;
> } else if (ARCH_IS_ARM(arch)) {
> - char *buf = line;
> - if (STRPREFIX(buf, "BogoMIPS")) {
> - char *p;
> - unsigned int ui;
> -
> - buf += 8;
> - while (*buf && c_isspace(*buf))
> - buf++;
> -
> - if (*buf != ':' || !buf[1]) {
> - virReportError(VIR_ERR_INTERNAL_ERROR,
> - "%s", _("parsing cpu MHz from cpuinfo"));
> - goto cleanup;
> - }
> -
> - if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0
> - /* Accept trailing fractional part. */
> - && (*p == '\0' || *p == '.' || c_isspace(*p)))
> - *mhz = ui;
> - }
> + if (virHostCPUGetInfoParseCPUFrequency(line, "BogoMIPS", mhz) < 0)
> + goto cleanup;
> } else if (ARCH_IS_S390(arch)) {
> /* s390x has no realistic value for CPU speed,
> * assign a value of zero to signify this */
> --
> 2.14.3
>
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list
>
I attach my take on this refactorization for comparison. Feel free to
take stuff you like. Or don't :)
--
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From 0a6cda1c0ff218585df811c952b149793f00ca17 Mon Sep 17 00:00:00 2001
From: Bjoern Walk <bwalk at linux.vnet.ibm.com>
Date: Thu, 30 Nov 2017 12:50:47 +0100
Subject: [PATCH 1/4] util: virhostcpu: factor out frequency parsing
All different architectures use the same copy-pasted code to parse
processor frequency information from /proc/cpuinfo. Let's extract that
code into a function to avoid repetition.
We now also tolerate if the parsing of /proc/cpuinfo is not successful
and just report a warning instead of bailing out and abandoning the rest
of the CPU information.
Reviewed-by: Marc Hartmayer <mhartmay at linux.vnet.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
Signed-off-by: Bjoern Walk <bwalk at linux.vnet.ibm.com>
---
src/util/virhostcpu.c | 136 +++++++++++++++++++++-----------------------------
1 file changed, 57 insertions(+), 79 deletions(-)
diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
index c485a972..0a4b241d 100644
--- a/src/util/virhostcpu.c
+++ b/src/util/virhostcpu.c
@@ -508,6 +508,61 @@ virHostCPUHasValidSubcoreConfiguration(int threads_per_subcore)
return ret;
}
+static int
+virHostCPUParseFrequencyLine(const char *str,
+ unsigned int *mhz)
+{
+ char *p;
+ unsigned int ui;
+
+ while (*str && c_isspace(*str))
+ str++;
+
+ if (*str != ':' || !str[1]) {
+ virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+ _("parsing cpu MHz from cpuinfo"));
+ return -1;
+ }
+
+ if (virStrToLong_ui(str + 1, &p, 10, &ui) == 0 &&
+ /* Accept trailing fractional part. */
+ (*p == '\0' || *p == '.' || c_isspace(*p)))
+ *mhz = ui;
+
+ return 0;
+}
+
+static int
+virHostCPUParseFrequency(FILE *cpuinfo,
+ virArch arch,
+ unsigned int *mhz)
+{
+ const char *prefix = NULL;
+ char line[1024];
+
+ if (ARCH_IS_X86(arch))
+ prefix = "cpu MHz";
+ else if (ARCH_IS_PPC(arch))
+ prefix = "clock";
+ else if (ARCH_IS_ARM(arch))
+ prefix = "BogoMIPS";
+
+ if (!prefix) {
+ VIR_WARN("Parser for /proc/cpuinfo needs to be adapted for your architecture");
+ return 1;
+ }
+
+ while (fgets(line, sizeof(line), cpuinfo) != NULL) {
+ if (!STRPREFIX(line, prefix))
+ continue;
+
+ if (virHostCPUParseFrequencyLine(line + strlen(prefix), mhz) < 0)
+ return -1;
+ }
+
+ return 0;
+}
+
int
virHostCPUGetInfoPopulateLinux(FILE *cpuinfo,
virArch arch,
@@ -520,7 +575,6 @@ virHostCPUGetInfoPopulateLinux(FILE *cpuinfo,
{
virBitmapPtr present_cpus_map = NULL;
virBitmapPtr online_cpus_map = NULL;
- char line[1024];
DIR *nodedir = NULL;
struct dirent *nodedirent = NULL;
int nodecpus, nodecores, nodesockets, nodethreads, offline = 0;
@@ -535,84 +589,8 @@ virHostCPUGetInfoPopulateLinux(FILE *cpuinfo,
*cpus = *nodes = *sockets = *cores = *threads = 0;
/* Start with parsing CPU clock speed from /proc/cpuinfo */
- while (fgets(line, sizeof(line), cpuinfo) != NULL) {
- if (ARCH_IS_X86(arch)) {
- char *buf = line;
- if (STRPREFIX(buf, "cpu MHz")) {
- char *p;
- unsigned int ui;
-
- buf += 7;
- while (*buf && c_isspace(*buf))
- buf++;
-
- if (*buf != ':' || !buf[1]) {
- virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
- _("parsing cpu MHz from cpuinfo"));
- goto cleanup;
- }
-
- if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 &&
- /* Accept trailing fractional part. */
- (*p == '\0' || *p == '.' || c_isspace(*p)))
- *mhz = ui;
- }
- } else if (ARCH_IS_PPC(arch)) {
- char *buf = line;
- if (STRPREFIX(buf, "clock")) {
- char *p;
- unsigned int ui;
-
- buf += 5;
- while (*buf && c_isspace(*buf))
- buf++;
-
- if (*buf != ':' || !buf[1]) {
- virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
- _("parsing cpu MHz from cpuinfo"));
- goto cleanup;
- }
-
- if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 &&
- /* Accept trailing fractional part. */
- (*p == '\0' || *p == '.' || c_isspace(*p)))
- *mhz = ui;
- /* No other interesting infos are available in /proc/cpuinfo.
- * However, there is a line identifying processor's version,
- * identification and machine, but we don't want it to be caught
- * and parsed in next iteration, because it is not in expected
- * format and thus lead to error. */
- }
- } else if (ARCH_IS_ARM(arch)) {
- char *buf = line;
- if (STRPREFIX(buf, "BogoMIPS")) {
- char *p;
- unsigned int ui;
-
- buf += 8;
- while (*buf && c_isspace(*buf))
- buf++;
-
- if (*buf != ':' || !buf[1]) {
- virReportError(VIR_ERR_INTERNAL_ERROR,
- "%s", _("parsing cpu MHz from cpuinfo"));
- goto cleanup;
- }
-
- if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0
- /* Accept trailing fractional part. */
- && (*p == '\0' || *p == '.' || c_isspace(*p)))
- *mhz = ui;
- }
- } else if (ARCH_IS_S390(arch)) {
- /* s390x has no realistic value for CPU speed,
- * assign a value of zero to signify this */
- *mhz = 0;
- } else {
- VIR_WARN("Parser for /proc/cpuinfo needs to be adapted for your architecture");
- break;
- }
- }
+ if (virHostCPUParseFrequency(cpuinfo, arch, mhz) < 0)
+ VIR_WARN("Unable to parse processor frequency information from /proc/cpuinfo");
/* Get information about what CPUs are present in the host and what
* CPUs are online, so that we don't have to so for each node */
--
2.14.3
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