[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

  • To: "Rob Gardner" <rob.gardner@xxxxxx>
  • From: "George Dunlap " <dunlapg@xxxxxxxxx>
  • Date: Thu, 15 Jun 2006 14:20:15 -0400
  • Cc: xen-tools@xxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx, rickey berkeley <rickey.berkeley@xxxxxxxxx>
  • Delivery-date: Thu, 15 Jun 2006 11:20:39 -0700
  • Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=kFcw5Azihp4lzNmu4MM0NaRzlZGU9C+wbOnok6A4UNUpj4m1BayxXMMAE6OUKL+rFn7rC6WzEh4Td+TUijpj1YAfu/BNQu7kYEsqdWEEWF3TK2o4h4SuIn85V2erqwP+zyaltNLpCyo+Vgc3ukACY1lA+IZpgh50CS0PuR1t7nU=
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

On 6/15/06, Rob Gardner <rob.gardner@xxxxxx> wrote:
I wouldn't call the amount of data 'huge'. Even on a very busy system,
where there are thousands of trace records being generated every second,
that's still a pretty small amount of data. (The size of a trace record
is something like 50 or 60 bytes.)

For the record, I think the trace record size in the trace buffers is
probably 32 bytes:

struct {
  unsigned long long rdtsc;  /* 8 */
  unsigned long event; /* + 4 = 12 */
  unsigned long data[5] /* + (4 * 5) = 32 */

The size on disk from xentrace is 36 bytes (it adds 4 bytes for the cpu).

If someone were really worried about copy time, one could write
something which uses raw disks (or, perhaps, the O_DIRECT flag) to DMA
data straight from the buffers to the disk.  But I'm not really
worried about it at this point. :-)


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.