File xen.sr-min_remaining.patch of Package xen

Overview Repositories Revisions Requests Users Attributes Meta

File xen.sr-min_remaining.patch of Package xen

From: Olaf Hering <olaf@aepfle.de>
Date: Thu, 7 Jan 2021 19:39:28 +0100
Subject: sr min_remaining

tools: add --min_remaining to libxl_domain_suspend

The decision to stop+move a domU to the new host must be based on two factors:
- the available network bandwidth for the migration stream
- the maximum time a workload within a domU can be savely suspended

Both values define how many dirty pages a workload may produce prior the
final stop+move.

The default value of 50 pages is much too low with todays network bandwidths.
On an idle 1GiB link these 200K will be transferred within ~2ms.

Give the admin a knob to adjust the point when the final stop+move will
be done, so he can base this decision on his own needs.

This patch adjusts xl(1) and the libxl API.
External users check LIBXL_HAVE_DOMAIN_SUSPEND_PROPS for the availibility
of the new .min_remaining property.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 docs/man/xl.1.pod.in              |  8 +++
 tools/include/libxl.h             |  1 +
 tools/libs/light/libxl_dom_save.c |  2 +-
 tools/libs/light/libxl_domain.c   |  1 +
 tools/libs/light/libxl_internal.h |  1 +
 tools/xl/xl_cmdtable.c            | 23 +++++----
 tools/xl/xl_migrate.c             |  9 +++-
 7 files changed, 32 insertions(+), 13 deletions(-)

--- a/docs/man/xl.1.pod.in
+++ b/docs/man/xl.1.pod.in
@@ -490,24 +490,32 @@ Leave the domain on the receive side paused after migration.
 
 =item B<-D>
 
 Preserve the B<domain-id> in the domain coniguration that is transferred
 such that it will be identical on the destination host, unless that
 configuration is overridden using the B<-C> option. Note that it is not
 possible to use this option for a 'localhost' migration.
 
 =item B<--max_iters> I<iterations>
 
 Number of copy iterations before final suspend+move (default: 5)
 
+=item B<--min_remaing> I<pages>
+
+Number of remaining dirty pages. If the number of dirty pages drops that
+low, the guest is suspended and the domU will finally be moved to I<host>.
+
+This allows the host admin to control for how long the domU will likely
+be suspended during transit.
+
 =back
 
 =item B<remus> [I<OPTIONS>] I<domain-id> I<host>
 
 Enable Remus HA or COLO HA for domain. By default B<xl> relies on ssh as a
 transport mechanism between the two hosts.
 
 B<NOTES>
 
 =over 4
 
 Remus support in xl is still in experimental (proof-of-concept) phase.
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -1787,24 +1787,25 @@ static inline int libxl_retrieve_domain_configuration_0x041200(
     libxl_retrieve_domain_configuration_0x041200
 #endif
 
 /*
  * LIBXL_HAVE_DOMAIN_SUSPEND_PROPS indicates that the
  * libxl_domain_suspend_props() function takes a props struct.
  */
 #define LIBXL_HAVE_DOMAIN_SUSPEND_PROPS 1
 
 typedef struct {
     uint32_t flags; /* LIBXL_SUSPEND_* */
     uint32_t max_iters;
+    uint32_t min_remaining;
 } libxl_domain_suspend_props;
 #define LIBXL_SUSPEND_DEBUG 1
 #define LIBXL_SUSPEND_LIVE 2
 
 int libxl_domain_suspend(libxl_ctx *ctx, uint32_t domid, int fd,
                          libxl_domain_suspend_props *props,
                          const libxl_asyncop_how *ao_how)
                          LIBXL_EXTERNAL_CALLERS_ONLY;
 #if defined(LIBXL_API_VERSION) && LIBXL_API_VERSION < 0x041600
 static inline int libxl_domain_suspend_0x041500(libxl_ctx *ctx, uint32_t domid,
                          int fd, int flags, /* LIBXL_SUSPEND_* */
                          const libxl_asyncop_how *ao_how)
--- a/tools/libs/light/libxl_dom_save.c
+++ b/tools/libs/light/libxl_dom_save.c
@@ -372,25 +372,25 @@ int libxl__save_emulator_xenstore_data(libxl__domain_save_state *dss,
 
     return rc;
 }
 
 static int libxl__domain_save_precopy_policy(struct precopy_stats stats, void *user)
 {
     libxl__save_helper_state *shs = user;
     libxl__domain_save_state *dss = shs->caller_state;
     STATE_AO_GC(dss->ao);
 
     LOGD(DEBUG, shs->domid, "iteration %u dirty_count %ld total_written %lu",
          stats.iteration, stats.dirty_count, stats.total_written);
-    if (stats.dirty_count >= 0 && stats.dirty_count < LIBXL_XGS_POLICY_TARGET_DIRTY_COUNT)
+    if (stats.dirty_count >= 0 && stats.dirty_count < dss->min_remaining)
         goto stop_copy;
     if (stats.iteration >= dss->max_iters)
         goto stop_copy;
     return XGS_POLICY_CONTINUE_PRECOPY;
 
 stop_copy:
     return XGS_POLICY_STOP_AND_COPY;
 }
 
 /*----- main code for saving, in order of execution -----*/
 
 void libxl__domain_save(libxl__egc *egc, libxl__domain_save_state *dss)
--- a/tools/libs/light/libxl_domain.c
+++ b/tools/libs/light/libxl_domain.c
@@ -516,24 +516,25 @@ int libxl_domain_suspend(libxl_ctx *ctx, uint32_t domid, int fd,
     }
 
     libxl__domain_save_state *dss;
     GCNEW(dss);
 
     dss->ao = ao;
     dss->callback = domain_suspend_cb;
 
     dss->domid = domid;
     dss->fd = fd;
     dss->type = type;
     dss->max_iters = props->max_iters ?: LIBXL_XGS_POLICY_MAX_ITERATIONS;
+    dss->min_remaining = props->min_remaining ?: LIBXL_XGS_POLICY_TARGET_DIRTY_COUNT;
     dss->live = props->flags & LIBXL_SUSPEND_LIVE;
     dss->debug = props->flags & LIBXL_SUSPEND_DEBUG;
     dss->checkpointed_stream = LIBXL_CHECKPOINTED_STREAM_NONE;
 
     rc = libxl__fd_flags_modify_save(gc, dss->fd,
                                      ~(O_NONBLOCK|O_NDELAY), 0,
                                      &dss->fdfl);
     if (rc < 0) goto out_err;
 
     libxl__domain_save(egc, dss);
     return AO_INPROGRESS;
 
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -3649,24 +3649,25 @@ struct libxl__domain_save_state {
     libxl__ao *ao;
     libxl__domain_save_cb *callback;
 
     uint32_t domid;
     int fd;
     int fdfl; /* original flags on fd */
     int recv_fd;
     libxl_domain_type type;
     int live;
     int debug;
     int checkpointed_stream;
     uint32_t max_iters;
+    uint32_t min_remaining;
     const libxl_domain_remus_info *remus;
     /* private */
     int rc;
     int xcflags;
     libxl__domain_suspend_state dsps;
     union {
         /* for Remus */
         libxl__remus_state rs;
         /* for COLO */
         libxl__colo_save_state css;
     };
     libxl__checkpoint_devices_state cds;
--- a/tools/xl/xl_cmdtable.c
+++ b/tools/xl/xl_cmdtable.c
@@ -156,35 +156,36 @@ const struct cmd_spec cmd_table[] = {
       &main_save, 0, 1,
       "Save a domain state to restore later",
       "[options] <Domain> <CheckpointFile> [<ConfigFile>]",
       "-h  Print this help.\n"
       "-c  Leave domain running after creating the snapshot.\n"
       "-p  Leave domain paused after creating the snapshot.\n"
       "-D  Store the domain id in the configuration."
     },
     { "migrate",
       &main_migrate, 0, 1,
       "Migrate a domain to another host",
       "[options] <Domain> <host>",
-      "-h              Print this help.\n"
-      "-C <config>     Send <config> instead of config file from creation.\n"
-      "-s <sshcommand> Use <sshcommand> instead of ssh.  String will be passed\n"
-      "                to sh. If empty, run <host> instead of ssh <host> xl\n"
-      "                migrate-receive [-d -e]\n"
-      "-e              Do not wait in the background (on <host>) for the death\n"
-      "                of the domain.\n"
-      "--debug         Enable verification mode.\n"
-      "-p              Do not unpause domain after migrating it.\n"
-      "-D              Preserve the domain id\n"
-      "--max_iters N   Number of copy iterations before final stop+move"
+      "-h                Print this help.\n"
+      "-C <config>       Send <config> instead of config file from creation.\n"
+      "-s <sshcommand>   Use <sshcommand> instead of ssh.  String will be passed\n"
+      "                  to sh. If empty, run <host> instead of ssh <host> xl\n"
+      "                  migrate-receive [-d -e]\n"
+      "-e                Do not wait in the background (on <host>) for the death\n"
+      "                  of the domain.\n"
+      "--debug           Enable verification mode.\n"
+      "-p                Do not unpause domain after migrating it.\n"
+      "-D                Preserve the domain id\n"
+      "--max_iters N     Number of copy iterations before final stop+move\n"
+      "--min_remaining N Number of remaining dirty pages before final stop+move"
     },
     { "restore",
       &main_restore, 0, 1,
       "Restore a domain from a saved state",
       "[options] [<ConfigFile>] <CheckpointFile>",
       "-h                       Print this help.\n"
       "-p                       Do not unpause domain after restoring it.\n"
       "-e                       Do not wait in the background for the death of the domain.\n"
       "-d                       Enable debug messages.\n"
       "-V, --vncviewer          Connect to the VNC display after the domain is created.\n"
       "-A, --vncviewer-autopass Pass VNC password to viewer via stdin."
     },
--- a/tools/xl/xl_migrate.c
+++ b/tools/xl/xl_migrate.c
@@ -170,36 +170,38 @@ static void migrate_do_preamble(int send_fd, int recv_fd, pid_t child,
         migration_child_report(recv_fd);
         exit(EXIT_FAILURE);
     }
 
     save_domain_core_writeconfig(send_fd, "migration stream",
                                  config_data, config_len);
 
 }
 
 static void migrate_domain(uint32_t domid, int preserve_domid,
                            const char *rune, int debug,
                            uint32_t max_iters,
+                           uint32_t min_remaining,
                            const char *override_config_file)
 {
     pid_t child = -1;
     int rc;
     int send_fd = -1, recv_fd = -1;
     char *away_domname;
     char rc_buf;
     uint8_t *config_data;
     int config_len;
     libxl_domain_suspend_props props = {
         .flags = LIBXL_SUSPEND_LIVE,
         .max_iters = max_iters,
+        .min_remaining = min_remaining,
         };
 
     save_domain_core_begin(domid, preserve_domid, override_config_file,
                            &config_data, &config_len);
 
     if (!config_len) {
         fprintf(stderr, "No config file stored for running domain and "
                 "none supplied - cannot migrate.\n");
         exit(EXIT_FAILURE);
     }
 
     child = create_migration_child(rune, &send_fd, &recv_fd);
@@ -536,27 +538,29 @@ int main_migrate_receive(int argc, char **argv)
 }
 
 int main_migrate(int argc, char **argv)
 {
     uint32_t domid;
     const char *config_filename = NULL;
     const char *ssh_command = "ssh";
     char *rune = NULL;
     char *host;
     int opt, daemonize = 1, monitor = 1, debug = 0, pause_after_migration = 0;
     int preserve_domid = 0;
     uint32_t max_iters = 0;
+    uint32_t min_remaining = 0;
     static struct option opts[] = {
         {"debug", 0, 0, 0x100},
         {"max_iters", 1, 0, 0x101},
+        {"min_remaining", 1, 0, 0x102},
         {"live", 0, 0, 0x200},
         COMMON_LONG_OPTS
     };
 
     SWITCH_FOREACH_OPT(opt, "FC:s:epD", opts, "migrate", 2) {
     case 'C':
         config_filename = optarg;
         break;
     case 's':
         ssh_command = optarg;
         break;
     case 'F':
@@ -569,24 +573,27 @@ int main_migrate(int argc, char **argv)
     case 'p':
         pause_after_migration = 1;
         break;
     case 'D':
         preserve_domid = 1;
         break;
     case 0x100: /* --debug */
         debug = 1;
         break;
     case 0x101: /* --max_iters */
         max_iters = atoi(optarg);
         break;
+    case 0x102: /* --min_remaining */
+        min_remaining = atoi(optarg);
+        break;
     case 0x200: /* --live */
         /* ignored for compatibility with xm */
         break;
     }
 
     domid = find_domain(argv[optind]);
     host = argv[optind + 1];
 
     bool pass_tty_arg = progress_use_cr || (isatty(2) > 0);
 
     if (!ssh_command[0]) {
         rune= host;
@@ -604,25 +611,25 @@ int main_migrate(int argc, char **argv)
         }
         xasprintf(&rune, "exec %s %s xl%s%s%.*s migrate-receive%s%s%s",
                   ssh_command, host,
                   pass_tty_arg ? " -t" : "",
                   timestamps ? " -T" : "",
                   verbose_len, verbose_buf,
                   daemonize ? "" : " -e",
                   debug ? " -d" : "",
                   pause_after_migration ? " -p" : "");
     }
 
     migrate_domain(domid, preserve_domid, rune, debug,
-                   max_iters, config_filename);
+                   max_iters, min_remaining, config_filename);
     return EXIT_SUCCESS;
 }
 
 int main_remus(int argc, char **argv)
 {
     uint32_t domid;
     int opt, rc, daemonize = 1;
     const char *ssh_command = "ssh";
     char *host = NULL, *rune = NULL;
     libxl_domain_remus_info r_info;
     int send_fd = -1, recv_fd = -1;
     pid_t child = -1;

Places

File xen.sr-min_remaining.patch of Package xen

Places