[PATCH V3 18/19] tools: add parallel parameter to virsh save command

[Jim Fehlig via Devel <devel@xxxxxxxxxxxxxxxxx>]

From: Claudio Fontana <cfontana@xxxxxxx>

Signed-off-by: Claudio Fontana <cfontana@xxxxxxx>
Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
 docs/manpages/virsh.rst | 12 +++++++++++-
 tools/virsh-domain.c    | 42 +++++++++++++++++++++++++++++++++++++----
 2 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
index 0eb1d6ea93..959393be13 100644
--- a/docs/manpages/virsh.rst
+++ b/docs/manpages/virsh.rst
@@ -3997,6 +3997,7 @@ save
 ::
 
    save domain state-file [--bypass-cache] [--xml file]
+      [--parallel] [--parallel-channels channels]
       [{--running | --paused}] [--verbose]
 
 Saves a running domain (RAM, but not disk state) to a state file so that
@@ -4004,8 +4005,11 @@ it can be restored
 later.  Once saved, the domain will no longer be running on the
 system, thus the memory allocated for the domain will be free for
 other domains to use.  ``virsh restore`` restores from this state file.
+
 If *--bypass-cache* is specified, the save will avoid the file system
-cache, although this may slow down the operation.
+cache. Depending on the specific scenario this may slow down or speed up
+the operation.
+
 
 The progress may be monitored using ``domjobinfo`` virsh command and canceled
 with ``domjobabort`` command (sent by another virsh instance). Another option
@@ -4027,6 +4031,12 @@ based on the state the domain was in when the save was done; passing
 either the *--running* or *--paused* flag will allow overriding which
 state the ``restore`` should use.
 
+*--parallel* option will cause the save data to be written to file
+over multiple parallel IO channels. The number of channels can be
+specified using *--parallel-channels*. Using parallel IO channels
+requires the use of ``sparse`` image save format. Parallel save may
+significantly reduce the time required to save large memory domains.
+
 Domain saved state files assume that disk images will be unchanged
 between the creation and restore point.  For a more complete system
 restore point, where the disk state is saved alongside the memory
diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index f3da2f903f..3b765a95b5 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -4145,6 +4145,14 @@ static const vshCmdOptDef opts_save[] = {
      .type = VSH_OT_BOOL,
      .help = N_("avoid file system cache when saving")
     },
+    {.name = "parallel",
+     .type = VSH_OT_BOOL,
+     .help = N_("enable parallel save")
+    },
+    {.name = "parallel-channels",
+     .type = VSH_OT_INT,
+     .help = N_("number of extra IO channels to use for parallel save")
+    },
     {.name = "xml",
      .type = VSH_OT_STRING,
      .unwanted_positional = true,
@@ -4175,6 +4183,11 @@ doSave(void *opaque)
     g_autoptr(virshDomain) dom = NULL;
     const char *name = NULL;
     const char *to = NULL;
+    virTypedParameterPtr params = NULL;
+    int nparams = 0;
+    int maxparams = 0;
+    int nchannels = 1;
+    int rv = -1;
     unsigned int flags = 0;
     const char *xmlfile = NULL;
     g_autofree char *xml = NULL;
@@ -4188,15 +4201,30 @@ doSave(void *opaque)
         goto out_sig;
 #endif /* !WIN32 */
 
-    if (vshCommandOptString(ctl, cmd, "file", &to) < 0)
-        goto out;
-
     if (vshCommandOptBool(cmd, "bypass-cache"))
         flags |= VIR_DOMAIN_SAVE_BYPASS_CACHE;
     if (vshCommandOptBool(cmd, "running"))
         flags |= VIR_DOMAIN_SAVE_RUNNING;
     if (vshCommandOptBool(cmd, "paused"))
         flags |= VIR_DOMAIN_SAVE_PAUSED;
+    if (vshCommandOptBool(cmd, "parallel"))
+        flags |= VIR_DOMAIN_SAVE_PARALLEL;
+
+    if (vshCommandOptString(ctl, cmd, "file", &to) < 0)
+        goto out;
+    if (to &&
+        virTypedParamsAddString(&params, &nparams, &maxparams,
+                                VIR_DOMAIN_SAVE_PARAM_FILE, to) < 0)
+        goto out;
+
+    if (flags & VIR_DOMAIN_SAVE_PARALLEL) {
+        if ((rv = vshCommandOptInt(ctl, cmd, "parallel-channels", &nchannels)) < 0)
+            goto out;
+
+        if (virTypedParamsAddInt(&params, &nparams, &maxparams,
+                                 VIR_DOMAIN_SAVE_PARAM_PARALLEL_CHANNELS, nchannels) < 0)
+            goto out;
+    }
 
     if (vshCommandOptString(ctl, cmd, "xml", &xmlfile) < 0)
         goto out;
@@ -4209,9 +4237,13 @@ doSave(void *opaque)
         vshReportError(ctl);
         goto out;
     }
+    if (xml &&
+        virTypedParamsAddString(&params, &nparams, &maxparams,
+                                VIR_DOMAIN_SAVE_PARAM_DXML, xml) < 0)
+        goto out;
 
     if (flags || xml) {
-        rc = virDomainSaveFlags(dom, to, xml, flags);
+        rc = virDomainSaveParams(dom, params, nparams, flags);
     } else {
         rc = virDomainSave(dom, to);
     }
@@ -4224,6 +4256,8 @@ doSave(void *opaque)
     data->ret = 0;
 
  out:
+    virTypedParamsFree(params, nparams);
+
 #ifndef WIN32
     pthread_sigmask(SIG_SETMASK, &oldsigmask, NULL);
  out_sig:
-- 
2.43.0