On Tue 21 Aug 2012 04:48:17 PM CST, Paolo Bonzini wrote:
Il 21/08/2012 10:23, Cong Meng ha scritto:
+static void sg_get_queue_limits(BlockDriverState *bs, const char *filename)
+{
+ DIR *ffs;
+ struct dirent *d;
+ char path[MAXPATHLEN];
+
+ snprintf(path, MAXPATHLEN,
+ "/sys/class/scsi_generic/sg%s/device/block/",
+ filename + strlen("/dev/sg"));
+
+ ffs = opendir(path);
+ if (!ffs) {
+ return;
+ }
+
+ for (;;) {
+ d = readdir(ffs);
+ if (!d) {
+ return;
+ }
+
+ if (strcmp(d->d_name, ".") == 0 || strcmp(d->d_name, "..") == 0) {
+ continue;
+ }
+
+ break;
+ }
+
+ closedir(ffs);
+
+ pstrcat(path, MAXPATHLEN, d->d_name);
+ pstrcat(path, MAXPATHLEN, "/queue/");
+
+ read_queue_limit(path, "max_sectors_kb", &bs->max_sectors);
+ read_queue_limit(path, "max_segments", &bs->max_segments);
+ read_queue_limit(path, "max_segment_size", &bs->max_segment_size);
+}
Using /sys/dev/block or /sys/dev/char seems easier, and lets you
retrieve the parameters for block devices too.
what do you mean with "block devices"? Using "/dev/sda" instead of
"/dev/sg0"?
However, I'm worried of the consequences this has for migration. You
could have the same physical disk accessed with two different HBAs, with
different limits. So I don't know if this can really be solved at all.
I know little about qemu migration now. The pending scsi commands will
be saved and
transfered to remote machine when starting migration?
Cong.
Paolo
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