On 03/08/2010 07:19 PM, Eric Blake wrote:
On 03/05/2010 12:06 PM, Chris Lalancette wrote:
+#define CPU_SYS_PATH "/sys/devices/system/cpu"
+ if (virAsprintf(&path, "%s/cpu%d/topology/thread_siblings", CPU_SYS_PATH, + cpu) < 0) {
Where is the documentation about what this file will contain? On my system, I see:
$ cat /sys/devices/system/cpu/cpu0/topology/thread_siblings_list 0 $ cat /sys/devices/system/cpu/cpu0/topology/thread_siblings 00000001 $ cat /sys/devices/system/cpu/cpu1/topology/thread_siblings_list 1 $ cat /sys/devices/system/cpu/cpu1/topology/thread_siblings 00000002
That is, I'm guessing that topology/thread_siblings_list is human-readable, while topology/thread_siblings is a hex bitmask. If it is indeed a 32-bit mask, then:
Actually, it's a much longer than 32-bit bit mask. On my RHEL-5 system, it looks like: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000002 (the commas are just to split it up visually; think of that above as one huge bitmask)
+ if (fgets(str, sizeof(str), pathfp) == NULL) { + virReportSystemError(errno, _("cannot read from %s"), path); + goto cleanup; + } + + i = 0; + while (str[i] != '\0') { + if (str[i] != '\n' && str[i] != ',') + ret += count_one_bits(str[i] - '0'); + i++; + }
...this loop is borked, since it is assuming that str[i] will be a digit, and is not looking for a-f. And why skipping comma? Shouldn't this instead be parsing the entire file contents as a single int, and only then calling count_one_bits once on the result?
So skipping the comma is correct here. You are right, though, that this is wrong for hex. For some reason I confused myself and thought the above was binary, not hex. I'll send a follow-up patch. Thanks, -- Chris Lalancette