Message ID | 1366579081-6857-5-git-send-email-mrhines@linux.vnet.ibm.com |
---|---|
State | New |
Headers | show |
On 04/21/2013 03:17 PM, mrhines@linux.vnet.ibm.com wrote: > From: "Michael R. Hines" <mrhines@us.ibm.com> > > This functions allows you to perform your own per-QEMUFileOps > calculation for the value of 'max_size'. > > For RDMA, this calculation artificially limits migration throughput > and needs to be done differently for high-throughput links. > > Signed-off-by: Michael R. Hines <mrhines@us.ibm.com> > --- > > +size_t qemu_get_max_size(QEMUFile *f, uint64_t transferred_bytes, > + uint64_t time_spent, uint64_t max_downtime) > +{ > + if (time_spent) { > + mbps = (((double) transferred_bytes * 8.0) / > + ((double) time_spent / 1000.0)) / 1000.0 / 1000.0; > + } else { > + mbps = -1.0; > + } > + > + if (f->ops->get_max_size) { > + return f->ops->get_max_size(f, f->opaque, > + transferred_bytes, time_spent, max_downtime); > + } > + > + return ((double) (transferred_bytes / time_spent)) * > + max_downtime / 1000000; Cast to double is too late; you've already suffered from integer division truncation when you compute (transferred_bytes/time_spent).
On 04/22/2013 04:20 PM, Eric Blake wrote: > On 04/21/2013 03:17 PM, mrhines@linux.vnet.ibm.com wrote: >> From: "Michael R. Hines" <mrhines@us.ibm.com> >> >> This functions allows you to perform your own per-QEMUFileOps >> calculation for the value of 'max_size'. >> >> For RDMA, this calculation artificially limits migration throughput >> and needs to be done differently for high-throughput links. >> >> Signed-off-by: Michael R. Hines <mrhines@us.ibm.com> >> --- >> >> +size_t qemu_get_max_size(QEMUFile *f, uint64_t transferred_bytes, >> + uint64_t time_spent, uint64_t max_downtime) >> +{ >> + if (time_spent) { >> + mbps = (((double) transferred_bytes * 8.0) / >> + ((double) time_spent / 1000.0)) / 1000.0 / 1000.0; >> + } else { >> + mbps = -1.0; >> + } >> + >> + if (f->ops->get_max_size) { >> + return f->ops->get_max_size(f, f->opaque, >> + transferred_bytes, time_spent, max_downtime); >> + } >> + >> + return ((double) (transferred_bytes / time_spent)) * >> + max_downtime / 1000000; > Cast to double is too late; you've already suffered from integer > division truncation when you compute (transferred_bytes/time_spent). > Good catch, thank you.
diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h index 70eb9bd..1803aeb 100644 --- a/include/migration/qemu-file.h +++ b/include/migration/qemu-file.h @@ -57,12 +57,22 @@ typedef int (QEMUFileGetFD)(void *opaque); typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, struct iovec *iov, int iovcnt, int64_t pos); +/* + * This function allows override of how to calculate max_size + * after each iteration. + */ +typedef size_t (QEMUFileMaxSizeFunc)(QEMUFile *f, void *opaque, + uint64_t transferred_bytes, + uint64_t time_spent, + uint64_t max_downtime); + typedef struct QEMUFileOps { QEMUFilePutBufferFunc *put_buffer; QEMUFileGetBufferFunc *get_buffer; QEMUFileCloseFunc *close; QEMUFileGetFD *get_fd; QEMUFileWritevBufferFunc *writev_buffer; + QEMUFileMaxSizeFunc *get_max_size; } QEMUFileOps; QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops); @@ -81,6 +91,8 @@ void qemu_put_byte(QEMUFile *f, int v); */ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size); double qemu_get_mbps(void); +size_t qemu_get_max_size(QEMUFile *f, uint64_t transferred_bytes, + uint64_t time_spent, uint64_t max_downtime); static inline void qemu_put_ubyte(QEMUFile *f, unsigned int v) diff --git a/migration.c b/migration.c index e2d73c4..48b5174 100644 --- a/migration.c +++ b/migration.c @@ -545,7 +545,8 @@ static void *migration_thread(void *opaque) uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes; uint64_t time_spent = current_time - initial_time - sleep_time; double bandwidth = transferred_bytes / time_spent; - max_size = bandwidth * migrate_max_downtime() / 1000000; + max_size = qemu_get_max_size(s->file, transferred_bytes, + time_spent, migrate_max_downtime()); DPRINTF("transferred %" PRIu64 " time_spent %" PRIu64 " bandwidth %g max_size %" PRId64 "\n", diff --git a/savevm.c b/savevm.c index 6fcad19..60776e5 100644 --- a/savevm.c +++ b/savevm.c @@ -647,6 +647,25 @@ int qemu_get_fd(QEMUFile *f) return -1; } +size_t qemu_get_max_size(QEMUFile *f, uint64_t transferred_bytes, + uint64_t time_spent, uint64_t max_downtime) +{ + if (time_spent) { + mbps = (((double) transferred_bytes * 8.0) / + ((double) time_spent / 1000.0)) / 1000.0 / 1000.0; + } else { + mbps = -1.0; + } + + if (f->ops->get_max_size) { + return f->ops->get_max_size(f, f->opaque, + transferred_bytes, time_spent, max_downtime); + } + + return ((double) (transferred_bytes / time_spent)) * + max_downtime / 1000000; +} + /** Closes the file * * Returns negative error value if any error happened on previous operations or