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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 7/9] tools/libxl,xl: add a --compress option to xl migrate
libxenguest can compress PAGE_DATA records with LZ4 when its caller
sets XCFLAGS_COMPRESS_LZ4, but libxl never sets it, so xl has no way to
ask for compression.
Add a LIBXL_SUSPEND_COMPRESS_LZ4 flag for libxl_domain_suspend(), pass
it to libxenguest as XCFLAGS_COMPRESS_LZ4, and expose it as
"xl migrate --compress".
Off by default: whether compressing pays off depends on how compressible
the guest's memory is and on the CPU headroom of both hosts, so the
caller decides. Only xl migrate gets the option; xl save and xl remus
never use LZ4.
The receiving side needs no option, as each PAGE_DATA record says
whether it is compressed. A receiver which cannot decompress rejects
the first compressed record, after it has created the domain, and the
migration fails with the guest still on the source. A sender whose
libxenguest was built without a supported liblz4 fails the migration
before sending any guest memory; libxl reports it as a suspend timeout.
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Marcus Granado <marcus.granado@xxxxxxxxxx>
---
Notes:
Changes in v2:
- Was v1 6/6. The libxl and xl code is unchanged; the help text and
man page now say both hosts need liblz4 support in libxenguest, and
CHANGELOG.md has an entry.
No LIBXL_HAVE_* macro: LIBXL_SUSPEND_COMPRESS_LZ4 is itself a #define,
so a caller can test for it with #ifdef LIBXL_SUSPEND_COMPRESS_LZ4.
CHANGELOG.md | 3 +++
docs/man/xl.1.pod.in | 8 ++++++++
tools/include/libxl.h | 1 +
tools/libs/light/libxl_dom_save.c | 4 +++-
tools/libs/light/libxl_domain.c | 1 +
tools/libs/light/libxl_internal.h | 1 +
tools/xl/xl_cmdtable.c | 2 ++
tools/xl/xl_migrate.c | 13 ++++++++++---
8 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 225397f128..4f1da5d9e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,9 @@ The format is based on [Keep a
Changelog](https://keepachangelog.com/en/1.0.0/)
afterwards.
### Added
+ - On x86:
+ - Optional LZ4 compression of the memory stream during migration
+ (xl migrate --compress).
### Removed
- On Arm:
diff --git a/docs/man/xl.1.pod.in b/docs/man/xl.1.pod.in
index 51405f4e33..b0439231e2 100644
--- a/docs/man/xl.1.pod.in
+++ b/docs/man/xl.1.pod.in
@@ -488,6 +488,14 @@ domain.
Display huge (!) amount of debug information during the migration process.
+=item B<--compress>
+
+Compress the memory stream using LZ4 inside libxenguest before sending it
+to the destination host. This can significantly reduce migration time on
+slow transports, and reduce dom0 CPU pressure during host evacuations when
+the migration data is subsequently encrypted or copied through pipes.
+Requires liblz4 support in libxenguest on both hosts.
+
=item B<-p>
Leave the domain on the receive side paused after migration.
diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index d294fb36bd..1114c8f8d1 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -1922,6 +1922,7 @@ int libxl_domain_suspend(libxl_ctx *ctx, uint32_t domid,
int fd,
LIBXL_EXTERNAL_CALLERS_ONLY;
#define LIBXL_SUSPEND_DEBUG 1
#define LIBXL_SUSPEND_LIVE 2
+#define LIBXL_SUSPEND_COMPRESS_LZ4 4
/*
* Only suspend domain, do not save its state to file, do not destroy it.
diff --git a/tools/libs/light/libxl_dom_save.c
b/tools/libs/light/libxl_dom_save.c
index d64fd64f2e..16b882ecf0 100644
--- a/tools/libs/light/libxl_dom_save.c
+++ b/tools/libs/light/libxl_dom_save.c
@@ -245,6 +245,7 @@ void libxl__domain_save(libxl__egc *egc,
libxl__domain_save_state *dss)
const libxl_domain_type type = dss->type;
const int live = dss->live;
const int debug = dss->debug;
+ const int compress_lz4 = dss->compress_lz4;
const libxl_domain_remus_info *const r_info = dss->remus;
libxl__srm_save_autogen_callbacks *const callbacks =
&dss->sws.shs.callbacks.save.a;
@@ -269,7 +270,8 @@ void libxl__domain_save(libxl__egc *egc,
libxl__domain_save_state *dss)
if (rc) goto out;
dss->xcflags = (live ? XCFLAGS_LIVE : 0)
- | (debug ? XCFLAGS_DEBUG : 0);
+ | (debug ? XCFLAGS_DEBUG : 0)
+ | (compress_lz4 ? XCFLAGS_COMPRESS_LZ4 : 0);
/* Disallow saving a guest with vNUMA configured because migration
* stream does not preserve node information.
diff --git a/tools/libs/light/libxl_domain.c b/tools/libs/light/libxl_domain.c
index 37fcd92871..86458a69c0 100644
--- a/tools/libs/light/libxl_domain.c
+++ b/tools/libs/light/libxl_domain.c
@@ -527,6 +527,7 @@ int libxl_domain_suspend(libxl_ctx *ctx, uint32_t domid,
int fd, int flags,
dss->type = type;
dss->live = flags & LIBXL_SUSPEND_LIVE;
dss->debug = flags & LIBXL_SUSPEND_DEBUG;
+ dss->compress_lz4 = flags & LIBXL_SUSPEND_COMPRESS_LZ4;
dss->checkpointed_stream = LIBXL_CHECKPOINTED_STREAM_NONE;
rc = libxl__fd_flags_modify_save(gc, dss->fd,
diff --git a/tools/libs/light/libxl_internal.h
b/tools/libs/light/libxl_internal.h
index b65e0064b9..ff7a334501 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -3598,6 +3598,7 @@ struct libxl__domain_save_state {
libxl_domain_type type;
int live;
int debug;
+ int compress_lz4;
int checkpointed_stream;
const libxl_domain_remus_info *remus;
/* private */
diff --git a/tools/xl/xl_cmdtable.c b/tools/xl/xl_cmdtable.c
index e48d5c5edc..aadca23a77 100644
--- a/tools/xl/xl_cmdtable.c
+++ b/tools/xl/xl_cmdtable.c
@@ -174,6 +174,8 @@ const struct cmd_spec cmd_table[] = {
"-e Do not wait in the background (on <host>) for the
death\n"
" of the domain.\n"
"--debug Print huge (!) amount of debug during the migration
process.\n"
+ "--compress Compress the memory stream using LZ4 in libxenguest.\n"
+ " Requires liblz4 support in libxenguest on both hosts.\n"
"-p Do not unpause domain after migrating it.\n"
"-D Preserve the domain id"
},
diff --git a/tools/xl/xl_migrate.c b/tools/xl/xl_migrate.c
index 4b4a379aa1..31a8cb4f32 100644
--- a/tools/xl/xl_migrate.c
+++ b/tools/xl/xl_migrate.c
@@ -177,7 +177,7 @@ static void migrate_do_preamble(int send_fd, int recv_fd,
pid_t child,
}
static void migrate_domain(uint32_t domid, int preserve_domid,
- const char *rune, int debug,
+ const char *rune, int debug, int compress_lz4,
const char *override_config_file)
{
pid_t child = -1;
@@ -206,6 +206,8 @@ static void migrate_domain(uint32_t domid, int
preserve_domid,
if (debug)
flags |= LIBXL_SUSPEND_DEBUG;
+ if (compress_lz4)
+ flags |= LIBXL_SUSPEND_COMPRESS_LZ4;
rc = libxl_domain_suspend(ctx, domid, send_fd, flags, NULL);
if (rc) {
fprintf(stderr, "migration sender: libxl_domain_suspend failed"
@@ -538,10 +540,11 @@ int main_migrate(int argc, char **argv)
char *rune = NULL;
char *host;
int opt, daemonize = 1, monitor = 1, debug = 0, pause_after_migration = 0;
- int preserve_domid = 0;
+ int preserve_domid = 0, compress_lz4 = 0;
static struct option opts[] = {
{"debug", 0, 0, 0x100},
{"live", 0, 0, 0x200},
+ {"compress", 0, 0, 0x300},
COMMON_LONG_OPTS
};
@@ -571,6 +574,9 @@ int main_migrate(int argc, char **argv)
case 0x200: /* --live */
/* ignored for compatibility with xm */
break;
+ case 0x300: /* --compress */
+ compress_lz4 = 1;
+ break;
}
domid = find_domain(argv[optind]);
@@ -602,7 +608,8 @@ int main_migrate(int argc, char **argv)
pause_after_migration ? " -p" : "");
}
- migrate_domain(domid, preserve_domid, rune, debug, config_filename);
+ migrate_domain(domid, preserve_domid, rune, debug, compress_lz4,
+ config_filename);
return EXIT_SUCCESS;
}
--
2.43.0
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