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cpumap: optimize for clients that don't need online count

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It turns out that calling virNodeGetCPUMap(conn, NULL, NULL, 0)
is both useful, and with Viktor's patches, common enough to
optimize.  Since this interface hasn't been released yet, we
can change the RPC call.

A bit more background on the optimization - learning the cpu count
is a single file read (/sys/devices/system/cpu/possible), but
learning the number of online cpus can possibly trigger a file
read per cpu, depending on the age of the kernel, and all wasted
if the caller passed NULL for both arguments.

* src/nodeinfo.c (nodeGetCPUMap): Avoid bitmap when not needed.
* src/remote/remote_protocol.x (remote_node_get_cpu_map_args):
Supply two separate flags for needed arguments.
* src/remote/remote_driver.c (remoteNodeGetCPUMap): Update
caller.
* daemon/remote.c (remoteDispatchNodeGetCPUMap): Likewise.
* src/remote_protocol-structs: Regenerate.
This commit is contained in:
Eric Blake
2012-11-01 17:55:43 -06:00
parent ba804d9fd1
commit 3d0130cbcc
5 changed files with 13 additions and 7 deletions
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8
daemon/remote.c
View File

@@ -4578,7 +4578,7 @@ remoteDispatchNodeGetCPUMap(virNetServerPtr server ATTRIBUTE_UNUSED,
remote_node_get_cpu_map_ret *ret)
{
unsigned char *cpumap = NULL;
unsigned int online;
unsigned int online = 0;
unsigned int flags;
int cpunum;
int rv = -1;
@@ -4592,13 +4592,13 @@ remoteDispatchNodeGetCPUMap(virNetServerPtr server ATTRIBUTE_UNUSED,
flags = args->flags;
cpunum = virNodeGetCPUMap(priv->conn, args->need_results ? &cpumap : NULL,
&online, flags);
cpunum = virNodeGetCPUMap(priv->conn, args->need_map ? &cpumap : NULL,
args->need_online ? &online : NULL, flags);
if (cpunum < 0)
goto cleanup;
/* 'serialize' return cpumap */
if (args->need_results) {
if (args->need_map) {
ret->cpumap.cpumap_len = VIR_CPU_MAPLEN(cpunum);
ret->cpumap.cpumap_val = (char *) cpumap;
cpumap = NULL;