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Code

Only probe qemu for machine types when binary changes

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By probing for qemu machine types, we increased the time of a
GetCapabilities call from 100us to a whopping 60ms.

This patch takes the approach of only probing for machine types
when the mtime of the emulator binary changed since the last time
the capabilities were generated.

* src/capabilities.h: cache the emulator binary mtime

* src/qemu_conf.c: add qemudGetOldMachines() to copy the machine
  types from the old caps struct if the mtime for the binary hasn't
  changed

* src/qemu_conf.h, src/qemu_driver.c: pass the old caps pointer to
  qemudCapsInit()
This commit is contained in:
Mark McLoughlin 2009-07-24 12:34:20 +01:00
parent 0f15d0344d
commit 707302b2cf
4 changed files with 95 additions and 9 deletions

1
src/capabilities.h

@ -49,6 +49,7 @@ struct _virCapsGuestDomainInfo {
char *loader;
int nmachines;
virCapsGuestMachinePtr *machines;
time_t emulator_mtime; /* do @machines need refreshing? */
};
typedef struct _virCapsGuestDomain virCapsGuestDomain;

95
src/qemu_conf.c

@ -456,8 +456,73 @@ rewait:
return ret;
}
static int
qemudGetOldMachines(const char *ostype,
const char *arch,
int wordsize,
const char *emulator,
time_t emulator_mtime,
virCapsPtr old_caps,
virCapsGuestMachinePtr **machines,
int *nmachines)
{
int i;
for (i = 0; i < old_caps->nguests; i++) {
virCapsGuestPtr guest = old_caps->guests[i];
virCapsGuestDomainInfoPtr info = &guest->arch.defaultInfo;
virCapsGuestMachinePtr *list;
if (!STREQ(ostype, guest->ostype) ||
!STREQ(arch, guest->arch.name) ||
wordsize != guest->arch.wordsize ||
!STREQ(emulator, info->emulator))
continue;
if (emulator_mtime != info->emulator_mtime) {
VIR_DEBUG("mtime on %s has changed, refreshing machine types",
info->emulator);
return 0;
}
/* It sucks to have to dup these, when we're most likely going
* to free the old caps anyway - except if an error occurs, we'll
* stick with the old caps.
* Also, if we get OOM here, just let the caller try and probe
* the binary directly, which will probably fail too.
*/
if (VIR_ALLOC_N(list, info->nmachines) < 0)
return 0;
for (i = 0; i < info->nmachines; i++) {
if (VIR_ALLOC(list[i]) < 0) {
virCapabilitiesFreeMachines(list, info->nmachines);
return 0;
}
if (info->machines[i]->name &&
!(list[i]->name = strdup(info->machines[i]->name))) {
virCapabilitiesFreeMachines(list, info->nmachines);
return 0;
}
if (info->machines[i]->canonical &&
!(list[i]->canonical = strdup(info->machines[i]->canonical))) {
virCapabilitiesFreeMachines(list, info->nmachines);
return 0;
}
}
*machines = list;
*nmachines = info->nmachines;
return 1;
}
return 0;
}
static int
qemudCapsInitGuest(virCapsPtr caps,
virCapsPtr old_caps,
const char *hostmachine,
const struct qemu_arch_info *info,
int hvm) {
@ -467,8 +532,10 @@ qemudCapsInitGuest(virCapsPtr caps,
int haskqemu = 0;
const char *kvmbin = NULL;
const char *binary = NULL;
time_t binary_mtime;
virCapsGuestMachinePtr *machines = NULL;
int nmachines = 0;
struct stat st;
/* Check for existance of base emulator, or alternate base
* which can be used with magic cpu choice
@ -507,6 +574,15 @@ qemudCapsInitGuest(virCapsPtr caps,
if (!binary)
return 0;
if (stat(binary, &st) == 0) {
binary_mtime = st.st_mtime;
} else {
char ebuf[1024];
VIR_WARN(_("Failed to stat %s, most peculiar : %s"),
binary, virStrerror(errno, ebuf, sizeof(ebuf)));
binary_mtime = 0;
}
if (info->machine) {
virCapsGuestMachinePtr machine;
@ -526,9 +602,16 @@ qemudCapsInitGuest(virCapsPtr caps,
machines[0] = machine;
nmachines = 1;
} else if (qemudProbeMachineTypes(binary, &machines, &nmachines) < 0)
} else {
int probe = 1;
if (old_caps && binary_mtime)
probe = !qemudGetOldMachines(hvm ? "hvm" : "xen", info->arch,
info->wordsize, binary, binary_mtime,
old_caps, &machines, &nmachines);
if (probe &&
qemudProbeMachineTypes(binary, &machines, &nmachines) < 0)
return -1;
}
/* We register kvm as the base emulator too, since we can
* just give -no-kvm to disable acceleration if required */
@ -548,6 +631,8 @@ qemudCapsInitGuest(virCapsPtr caps,
return -1;
}
guest->arch.defaultInfo.emulator_mtime = binary_mtime;
if (hvm) {
if (virCapabilitiesAddGuestDomain(guest,
"qemu",
@ -597,7 +682,7 @@ qemudCapsInitGuest(virCapsPtr caps,
return 0;
}
virCapsPtr qemudCapsInit(void) {
virCapsPtr qemudCapsInit(virCapsPtr old_caps) {
struct utsname utsname;
virCapsPtr caps;
int i;
@ -626,7 +711,7 @@ virCapsPtr qemudCapsInit(void) {
/* First the pure HVM guests */
for (i = 0 ; i < ARRAY_CARDINALITY(arch_info_hvm) ; i++)
if (qemudCapsInitGuest(caps,
if (qemudCapsInitGuest(caps, old_caps,
utsname.machine,
&arch_info_hvm[i], 1) < 0)
goto no_memory;
@ -639,7 +724,7 @@ virCapsPtr qemudCapsInit(void) {
if (STREQ(arch_info_xen[i].arch, utsname.machine) ||
(STREQ(utsname.machine, "x86_64") &&
STREQ(arch_info_xen[i].arch, "i686"))) {
if (qemudCapsInitGuest(caps,
if (qemudCapsInitGuest(caps, old_caps,
utsname.machine,
&arch_info_xen[i], 0) < 0)
goto no_memory;

2
src/qemu_conf.h

@ -125,7 +125,7 @@ struct qemud_driver {
int qemudLoadDriverConfig(struct qemud_driver *driver,
const char *filename);
virCapsPtr qemudCapsInit (void);
virCapsPtr qemudCapsInit (virCapsPtr old_caps);
int qemudExtractVersion (virConnectPtr conn,
struct qemud_driver *driver);

4
src/qemu_driver.c

@ -516,7 +516,7 @@ qemudStartup(int privileged) {
virStrerror(-rc, buf, sizeof(buf)));
}
if ((qemu_driver->caps = qemudCapsInit()) == NULL)
if ((qemu_driver->caps = qemudCapsInit(NULL)) == NULL)
goto out_of_memory;
if (qemudLoadDriverConfig(qemu_driver, driverConf) < 0) {
@ -2440,7 +2440,7 @@ static char *qemudGetCapabilities(virConnectPtr conn) {
char *xml = NULL;
qemuDriverLock(driver);
if ((caps = qemudCapsInit()) == NULL) {
if ((caps = qemudCapsInit(qemu_driver->caps)) == NULL) {
virReportOOMError(conn);
goto cleanup;
}