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Re: [Xen-devel] Hi,something about the xentrace tool

  • To: "Rob Gardner" <rob.gardner@xxxxxx>
  • From: "George Dunlap " <dunlapg@xxxxxxxxx>
  • Date: Wed, 21 Jun 2006 15:02:43 -0400
  • Cc: xen-tools@xxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Wed, 21 Jun 2006 12:04:07 -0700
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On 6/19/06, Rob Gardner <rob.gardner@xxxxxx> wrote:
I am glad to discover that I misunderstood you. ;) But I am still having
trouble understanding what the actual problem is, or even if one exists.

Well, I ran some tests, and no problem exists, yet.  Running the following:

# time xentrace -e 0x81000 /tmp/test22-passmark.trace
change evtmask to 0x81000

real    7m15.456s
user    0m0.080s
sys     0m0.050s
# ls -l /tmp/test22-passmark.trace
-rw-r--r-- 1 root root 2654091720 Jun 21 14:49 /tmp/test22-passmark.trace

So although 2.6 gigabytes was generated in 7 minutes, the total time
spent in user and system (if the numbers time report are accurate) was
less than .13 seconds.

The only potential issues would be with cache trashing -- both the
buffer cache (from plain writes to the file), and the cpu caches (from
copying the data).  If anyone finds a workload this is a problem for,
we can look at it then.


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