From: Olaf Hering Date: Thu, 7 Jan 2021 19:39:28 +0100 Subject: libxc 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 --- 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 @@ -505,6 +505,14 @@ possible to use this option for a 'local Number of copy iterations before final suspend+move (default: 5) +=item B<--min_remaing> I + +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. + +This allows the host admin to control for how long the domU will likely +be suspended during transit. + =back =item B [I] I I --- a/tools/include/libxl.h +++ b/tools/include/libxl.h @@ -1859,6 +1859,7 @@ static inline int libxl_retrieve_domain_ typedef struct { uint32_t flags; /* LIBXL_SUSPEND_* */ uint32_t max_iters; + uint32_t min_remaining; } libxl_domain_suspend_suse_properties; #define LIBXL_SUSPEND_DEBUG 1 #define LIBXL_SUSPEND_LIVE 2 --- a/tools/libs/light/libxl_dom_save.c +++ b/tools/libs/light/libxl_dom_save.c @@ -381,7 +381,7 @@ static int libxl__domain_save_precopy_po 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; --- a/tools/libs/light/libxl_domain.c +++ b/tools/libs/light/libxl_domain.c @@ -525,6 +525,7 @@ static int do_libxl_domain_suspend(libxl 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; --- a/tools/libs/light/libxl_internal.h +++ b/tools/libs/light/libxl_internal.h @@ -3654,6 +3654,7 @@ struct libxl__domain_save_state { int debug; int checkpointed_stream; uint32_t max_iters; + uint32_t min_remaining; const libxl_domain_remus_info *remus; /* private */ int rc; --- a/tools/xl/xl_cmdtable.c +++ b/tools/xl/xl_cmdtable.c @@ -166,17 +166,18 @@ const struct cmd_spec cmd_table[] = { &main_migrate, 0, 1, "Migrate a domain to another host", "[options] ", - "-h Print this help.\n" - "-C Send instead of config file from creation.\n" - "-s Use instead of ssh. String will be passed\n" - " to sh. If empty, run instead of ssh xl\n" - " migrate-receive [-d -e]\n" - "-e Do not wait in the background (on ) 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 Send instead of config file from creation.\n" + "-s Use instead of ssh. String will be passed\n" + " to sh. If empty, run instead of ssh xl\n" + " migrate-receive [-d -e]\n" + "-e Do not wait in the background (on ) 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, --- a/tools/xl/xl_migrate.c +++ b/tools/xl/xl_migrate.c @@ -179,6 +179,7 @@ static void migrate_do_preamble(int send 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; @@ -191,6 +192,7 @@ static void migrate_domain(uint32_t domi libxl_domain_suspend_suse_properties props = { .flags = LIBXL_SUSPEND_LIVE, .max_iters = max_iters, + .min_remaining = min_remaining, }; save_domain_core_begin(domid, preserve_domid, override_config_file, @@ -545,9 +547,11 @@ int main_migrate(int argc, char **argv) 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 }; @@ -578,6 +582,9 @@ int main_migrate(int argc, char **argv) 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; @@ -613,7 +620,7 @@ int main_migrate(int argc, char **argv) } migrate_domain(domid, preserve_domid, rune, debug, - max_iters, config_filename); + max_iters, min_remaining, config_filename); return EXIT_SUCCESS; }