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/*
* Linux DTrace
* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
#!/usr/sbin/dtrace -s
# pragma D option quiet
/*
* SYNOPSIS
* sudo ./507aggregations-trunc5.d
*
* DESCRIPTION
* Here, is another use of trunc() -- with an additional
* argument to focus attention on the top values.
*/
BEGIN
{
/*
* The mask will change size. When it is wide, it will
* spread values over many keys. When it is narrow, it
* will concentrate values over a few keys. So, some
* keys will get many values, while others will get few.
*/
mask = 255;
}
tick-100hz
{
/* the aggregation */
@[timestamp & mask] = count();
/* update the mask */
mask >>= 1;
mask = (mask == 0) ? 255 : mask;
}
tick-1sec
{
printf("entire result\n");
printa(" %3d %@3d\n", @);
trunc(@, 5);
printf("top 5 keys\n");
printa(" %3d %@3d\n", @);
/*
* On exit, we will no longer print the aggregation
* by default, since it was just printed.
*/
exit(0);
}
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