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Support memory ballooning in QEMU

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This commit is contained in:
Daniel P. Berrange 2009-03-27 11:44:29 +00:00
parent 97230f6a35
commit cb7593bd19
3 changed files with 137 additions and 10 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
Fri Mar 27 11:44:22 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
Support memory ballooning in QEMU
* src/qemu_conf.c: Fix initial QEMU startup memory allocation
to be based on 'max memory'
* src/qemu_driver.c: Balloon down allocation to 'memory'
setting at startup. Implement virDomainSetMemory() for running
guests via memory balloon. Report mem current usage by querying
memory balloon.
Tue Mar 24 11:14:22 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
* src/capabilities.c, file src/capabilities.h,

6
src/qemu_conf.c
View File

@ -927,7 +927,11 @@ int qemudBuildCommandLine(virConnectPtr conn,
} \
} while (0)
snprintf(memory, sizeof(memory), "%lu", vm->def->memory/1024);
/* Set '-m MB' based on maxmem, because the lower 'memory' limit
* is set post-startup using the balloon driver. If balloon driver
* is not supported, then they're out of luck anyway
*/
snprintf(memory, sizeof(memory), "%lu", vm->def->maxmem/1024);
snprintf(vcpus, sizeof(vcpus), "%lu", vm->def->vcpus);
snprintf(domid, sizeof(domid), "%d", vm->def->id);
pidfile = virFilePid(driver->stateDir, vm->def->name);

131
src/qemu_driver.c
View File

@ -122,6 +122,9 @@ static int qemudMonitorCommandExtra(const virDomainObjPtr vm,
const char *extra,
const char *extraPrompt,
char **reply);
static int qemudDomainSetMemoryBalloon(virConnectPtr conn,
virDomainObjPtr vm,
unsigned long newmem);
static struct qemud_driver *qemu_driver = NULL;
@ -1481,6 +1484,7 @@ static int qemudStartVMDaemon(virConnectPtr conn,
(qemudDetectVcpuPIDs(conn, vm) < 0) ||
(qemudInitCpus(conn, vm, migrateFrom) < 0) ||
(qemudInitPasswords(conn, driver, vm) < 0) ||
(qemudDomainSetMemoryBalloon(conn, vm, vm->def->memory) < 0) ||
(qemudSaveDomainStatus(conn, qemu_driver, vm) < 0)) {
qemudShutdownVMDaemon(conn, driver, vm);
return -1;
@ -2410,6 +2414,95 @@ cleanup:
return ret;
}
/* The reply from QEMU contains 'ballon: actual=421' where value is in MB */
#define BALLOON_PREFIX "balloon: actual="
/*
* Returns: 0 if balloon not supported, +1 if balloon query worked
* or -1 on failure
*/
static int qemudDomainGetMemoryBalloon(virConnectPtr conn,
virDomainObjPtr vm,
unsigned long *currmem) {
char *reply = NULL;
int ret = -1;
char *offset;
if (qemudMonitorCommand(vm, "info balloon", &reply) < 0) {
qemudReportError(conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
"%s", _("could not query memory balloon allocation"));
goto cleanup;
}
DEBUG ("balloon reply: '%s'", reply);
if ((offset = strstr(reply, BALLOON_PREFIX)) != NULL) {
unsigned int memMB;
char *end;
offset += strlen(BALLOON_PREFIX);
if (virStrToLong_ui(offset, &end, 10, &memMB) < 0) {
qemudReportError(conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
"%s", _("could not parse memory balloon allocation"));
goto cleanup;
}
*currmem = memMB * 1024;
ret = 1;
} else {
/* We don't raise an error here, since its to be expected that
* many QEMU's don't support ballooning
*/
ret = 0;
}
cleanup:
VIR_FREE(reply);
return ret;
}
/*
* Returns: 0 if balloon not supported, +1 if balloon query worked
* or -1 on failure
*/
static int qemudDomainSetMemoryBalloon(virConnectPtr conn,
virDomainObjPtr vm,
unsigned long newmem) {
char *cmd;
char *reply = NULL;
int ret = -1;
/*
* 'newmem' is in KB, QEMU monitor works in MB, and we all wish
* we just worked in bytes with unsigned long long everywhere.
*/
if (virAsprintf(&cmd, "balloon %lu", (newmem / 1024)) < 0) {
virReportOOMError(conn);
goto cleanup;
}
if (qemudMonitorCommand(vm, cmd, &reply) < 0) {
qemudReportError(conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
"%s", _("could not balloon memory allocation"));
VIR_FREE(cmd);
goto cleanup;
}
VIR_FREE(cmd);
/* If the command failed qemu prints: 'unknown command'
* No message is printed on success it seems */
DEBUG ("balloon reply: %s", reply);
if (strstr(reply, "\nunknown command:")) {
/* Don't set error - it is expected memory balloon fails on many qemu */
ret = 0;
} else {
ret = 1;
}
cleanup:
VIR_FREE(reply);
return ret;
}
static int qemudDomainSetMemory(virDomainPtr dom, unsigned long newmem) {
struct qemud_driver *driver = dom->conn->privateData;
virDomainObjPtr vm;
@ -2427,20 +2520,21 @@ static int qemudDomainSetMemory(virDomainPtr dom, unsigned long newmem) {
goto cleanup;
}
if (virDomainIsActive(vm)) {
qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT,
"%s", _("cannot set memory of an active domain"));
goto cleanup;
}
if (newmem > vm->def->maxmem) {
qemudReportError(dom->conn, dom, NULL, VIR_ERR_INVALID_ARG,
"%s", _("cannot set memory higher than max memory"));
goto cleanup;
}
vm->def->memory = newmem;
ret = 0;
if (virDomainIsActive(vm)) {
ret = qemudDomainSetMemoryBalloon(dom->conn, vm, newmem);
if (ret == 0)
qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT,
"%s", _("cannot set memory of an active domain"));
} else {
vm->def->memory = newmem;
ret = 0;
}
cleanup:
if (vm)
@ -2453,6 +2547,8 @@ static int qemudDomainGetInfo(virDomainPtr dom,
struct qemud_driver *driver = dom->conn->privateData;
virDomainObjPtr vm;
int ret = -1;
int err;
unsigned long balloon;
qemuDriverLock(driver);
vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@ -2474,8 +2570,16 @@ static int qemudDomainGetInfo(virDomainPtr dom,
}
}
err = qemudDomainGetMemoryBalloon(dom->conn, vm, &balloon);
if (err < 0)
goto cleanup;
info->maxMem = vm->def->maxmem;
info->memory = vm->def->memory;
if (err == 0)
/* Balloon not supported, so maxmem is always the allocation */
info->memory = vm->def->maxmem;
else
info->memory = balloon;
info->nrVirtCpu = vm->def->vcpus;
ret = 0;
@ -3170,6 +3274,8 @@ static char *qemudDomainDumpXML(virDomainPtr dom,
struct qemud_driver *driver = dom->conn->privateData;
virDomainObjPtr vm;
char *ret = NULL;
unsigned long balloon;
int err;
qemuDriverLock(driver);
vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@ -3181,6 +3287,13 @@ static char *qemudDomainDumpXML(virDomainPtr dom,
goto cleanup;
}
/* Refresh current memory based on balloon info */
err = qemudDomainGetMemoryBalloon(dom->conn, vm, &balloon);
if (err < 0)
goto cleanup;
if (err > 0)
vm->def->memory = balloon;
ret = virDomainDefFormat(dom->conn,
(flags & VIR_DOMAIN_XML_INACTIVE) && vm->newDef ?
vm->newDef : vm->def,