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s390/sclp: cache the sclp device

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With the current code a simple sclp command takes about 13000 ns
The biggest part seems to be the resolver of the object model. By
caching the sclp device the time for an sclp command goes down to
2500ns. Talking about real life scenarios, this change doubles
the speed of the sclp console when sending single bytes outputs
to /dev/console.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2016-08-10 12:14:19 +02:00 committed by Cornelia Huck
parent 0c2a16a4dc
commit 989fd865f5
1 changed files with 6 additions and 1 deletions
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7
hw/s390x/sclp.c
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@ -26,7 +26,12 @@
static inline SCLPDevice *get_sclp_device(void)
{
return SCLP(object_resolve_path_type("", TYPE_SCLP, NULL));
static SCLPDevice *sclp;
if (!sclp) {
sclp = SCLP(object_resolve_path_type("", TYPE_SCLP, NULL));
}
return sclp;
}
/* Provide information about the configuration, CPUs and storage */