Bug 1922768

Summary:	dstat count is one off
Product:	[Fedora] Fedora	Reporter:	Georg Sauthoff <fedora>
Component:	pcp	Assignee:	Nathan Scott <nathans>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	33	CC:	agerstmayr, mgoodwin, nathans
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	pcp-5.2.5-2.fc33 pcp-5.2.5-2.fc32	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-02-24 20:39:54 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Georg Sauthoff 2021-01-31 14:27:00 UTC

Description of problem:
When invoking dstat with an explicit count of n it actually just prints n-1 updates.


Version-Release number of selected component (if applicable):
pcp-system-tools-5.2.3-1.fc33.x86_64

How reproducible:
always

Steps to Reproduce:
1. dstat 1 3
2. dstat 1 1
3.

Actual results:
You did not select any stats, using -cdngy by default.
----total-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai stl| read  writ| recv  send|  in   out | int   csw 
 15   4  80   0   0|   0   811k|  25k 1119B|   0     0 |3721  4738 
 18   5  77   0   0|   0     0 |  27k  980B|   0     0 |3789  4659

You did not select any stats, using -cdngy by default.
----total-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai stl| read  writ| recv  send|  in   out | int   csw 



Expected results:
Three updates, in total - i.e. something like this:

You did not select any stats, using -cdngy by default.
----total-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai stl| read  writ| recv  send|  in   out | int   csw 
 15   4  80   0   0|   0   811k|  25k 1119B|   0     0 |3721  4738 
 18   5  77   0   0|   0     0 |  27k  980B|   0     0 |3789  4659
 16   5  77   0   0|   0     0 |  27k 1980B|   0     0 |3780  4653

Followed by one update:

You did not select any stats, using -cdngy by default.
----total-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai stl| read  writ| recv  send|  in   out | int   csw 
 17   5  77   0   0|   0     0 |  24k  909B|   0     0 |3937  4912


Additional info:

The result of the second invocation seems to be a regression - cf. #1449687

Note that the current dstat behavior is also inconsistent with similar tools such as vmstat.

Comment 1 Nathan Scott 2021-01-31 22:56:08 UTC

Thanks Georg!

This patch seems to resolve the issue, lightly tested only so far:

diff --git a/src/pcp/dstat/pcp-dstat.py b/src/pcp/dstat/pcp-dstat.py
index b8d786bd5..e5c20fba2 100755
--- a/src/pcp/dstat/pcp-dstat.py
+++ b/src/pcp/dstat/pcp-dstat.py
@@ -705,7 +705,7 @@ class DstatTool(object):
                 sys.exit(1)
         if len(operands) > 1:
             try:
-                self.samples = int(operands[1])
+                self.samples = int(operands[1]) + 1
             except:
                 sys.stderr.write("Invalid sample count '%s'\n" % operands[1])
                 sys.exit(1)


I'll do some more testing (haven't checked archives yet, nor updated the regression tests) and get this fixed in pcp-5.2.4.

cheers.

Comment 2 Fedora Update System 2021-02-15 00:05:58 UTC

FEDORA-2021-c64d2658a0 has been submitted as an update to Fedora 33. https://bodhi.fedoraproject.org/updates/FEDORA-2021-c64d2658a0

Comment 3 Fedora Update System 2021-02-15 00:06:23 UTC

FEDORA-2021-4e2b6f6f82 has been submitted as an update to Fedora 32. https://bodhi.fedoraproject.org/updates/FEDORA-2021-4e2b6f6f82

Comment 4 Fedora Update System 2021-02-15 01:14:31 UTC

FEDORA-2021-c64d2658a0 has been pushed to the Fedora 33 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --advisory=FEDORA-2021-c64d2658a0`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2021-c64d2658a0

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2021-02-16 01:18:23 UTC

FEDORA-2021-4e2b6f6f82 has been pushed to the Fedora 32 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --advisory=FEDORA-2021-4e2b6f6f82`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2021-4e2b6f6f82

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2021-02-24 20:39:54 UTC

FEDORA-2021-c64d2658a0 has been pushed to the Fedora 33 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 7 Fedora Update System 2021-02-24 20:44:25 UTC

FEDORA-2021-4e2b6f6f82 has been pushed to the Fedora 32 stable repository.
If problem still persists, please make note of it in this bug report.