!sos.DumpHeap -stat -cache -gen 2 ==> high CPU and PageFaults

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Loy - 06 Nov 2006 13:31 GMT

I have dump file
I got the output of !dh -stat -cache (took few minutes)
Summary: Total 6,011,900 objects, Total size: 581,098,460
About 1400 types

The problem is when I try to the same summary for Gen 2 only
Running "!dh -stat -cache -gen 2"
Takes verrrry long time with ~50% cpu usage and thousands of pagefaults
per second all that time

I expected it to be much faster - as the first run should have cached
the needed data...
but actually - it seems like a way more expensive operation - why?

1. Is it a known issue?
2. Is there something I can do about it (beside letting it run through
the night)?

More information:
- filever:
--a-- W32i APP ENU 6.4.7.0 shp 374,272 01-10-2005
windbg.exe
--a-- W32i APP ENU 6.4.7.0 shp 54,784 01-10-2005 cdb.exe
--a-- W32i DLL ENU 6.4.7.0 shp 882,688 01-10-2005 sos.dll

I created the dump using AdPlus.vbs -hang

Loy

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Loy - 06 Nov 2006 16:36 GMT

It is still running:
CPU time: 1:48:11
Page Faults: 84,976,960
PfDelta (per second): more than 12,000

Any help will be appreciated

Loy

> I have dump file
> I got the output of !dh -stat -cache (took few minutes)
[quoted text clipped - 24 lines]
>
> Loy

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Willy Denoyette [MVP] - 06 Nov 2006 16:50 GMT

|I have dump file
| I got the output of !dh -stat -cache (took few minutes)
[quoted text clipped - 24 lines]
|
| Loy

How much RAM do you have in your box? and how much memory is there
available. It looks like after the first run, you have paged-out the
debuggee's managed heap (or part of). With a GH heap size of +500 MB you
need two times this amount of memory.

Willy.

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Loy - 12 Nov 2006 09:44 GMT

The question is still open - why, when adding the flag "-gen 2" it
takes hours with thousands of PF per second?
- while without this flag is takes upto 2 minutes? and why "-cache"
flag in the first time does not help reducing this time?

Willy

Thanks for your response.
Sorry I wasn't able to answer earlier (I wasn't feeling well)

Quote" "you have paged-out the debuggee's managed heap (or part of).
With a GH heap size of +500 MB you need two times this amount of
memory."

I have 1GB pf ram
Before starting !dh - Available physical memory: 524,744[k] (repotrted
by taskmgr)

I can find PC with 2GB of memory - but I'm not sure even this would be
enough

Loy

> |I have dump file
> | I got the output of !dh -stat -cache (took few minutes)
[quoted text clipped - 31 lines]
>
> Willy.

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Dekel.FunStaff@gmail.com - 13 Nov 2006 08:23 GMT

Still waiting for microsoft (MSFT) response

Additional information:
While TaskMgr.exe shows count of about 15,000 in the "PF delta" for
windbg.exe
Perfmon Pages / sec shows ~10 (for all processes together)

I assume this means that the high number means "soft page faults"

This still does not explain why does it takes two hours with the flag
"-gen 2" Vs. 2 minutes without it

Does anyone else tried this command on large scale application (memory
footprint of more than 500MB mainly for managed objects)?

Loy

> The question is still open - why, when adding the flag "-gen 2" it
> takes hours with thousands of PF per second?
[quoted text clipped - 54 lines]
> >
> > Willy.

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!sos.DumpHeap -stat -cache -gen 2 ==> high CPU and PageFaults

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