2234460 – Slow ssh connection when using password authentication due to a large amount of "close" syscall

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Bug 2234460 - Slow ssh connection when using password authentication due to a large amount of "close" syscall

Summary: Slow ssh connection when using password authentication due to a large amount ...

Keywords:
Status:	CLOSED MIGRATED
Alias:	None
Product:	Red Hat Enterprise Linux 9
Classification:	Red Hat
Component:	pam
Sub Component:
Version:	unspecified
Hardware:	All
OS:	Linux
Priority:	unspecified
Severity:	medium
Target Milestone:	rc
Target Release:	---
Assignee:	Iker Pedrosa
QA Contact:	sssd-qe
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+	depends on / blocked

Reported:	2023-08-24 13:55 UTC by Nicolas Bourgeois
Modified:	2023-09-19 14:04 UTC (History)
CC List:	2 users (show)
Fixed In Version:
Doc Type:	If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:	2023-09-19 14:04:49 UTC
Type:	Bug
Target Upstream Version:
Embargoed:
Dependent Products:

Attachments	(Terms of Use)

Links
System	ID	Priority	Status	Summary	Last Updated
Red Hat Bugzilla	1737812	low	CLOSED	optimize closing fds when spawning handlers in PAM by looking up opened handles via /proc/self/fd	2024-07-23 11:04:20 UTC
Red Hat Issue Tracker	RHEL-5099	None	Migrated	None	2023-09-19 14:03:01 UTC
Red Hat Issue Tracker	RHELPLAN-166438	None	None	None	2023-08-24 13:59:14 UTC
Red Hat Issue Tracker	SSSD-6655	None	None	None	2023-08-24 18:56:47 UTC

Description Nicolas Bourgeois 2023-08-24 13:55:03 UTC

Description of problem:
Connecting via ssh to a server with a password is longer with RHEL 9 compared to RHEL 8



IT seemed to be resolved in RHEL 8 with the patch pam-1.3.1-fds-closing.patch (RHBZ1737812), but the fix has been reverted upstream and is not part of the code anymore.

Version-Release number of selected component (if applicable):
9.0, 9.1 and 9.2

How reproducible:
Connect using a password authentication


Actual results:
With RHEL 9, sshd spends 25% of its time running the close syscall :
	RHEL 9 :
		% time     seconds  usecs/call     calls    errors syscall
		------ ----------- ----------- --------- --------- ----------------
		 71.81    1.680497       35755        47        21 wait4
		 25.48    0.596416           4    131894    131057 close
		  0.48    0.011248          11       979       335 openat
		  0.31    0.007196         359        20           execve
		...

	RHEL 8 :
		% time     seconds  usecs/call     calls    errors syscall
		------ ----------- ----------- --------- --------- ----------------
		 81.89    0.099364        1505        66        31 wait4
		  2.64    0.003209           4       773       208 openat
		  2.53    0.003064         139        22           execve
		  2.26    0.002739          80        34           clone
		  1.21    0.001467          27        53           socket
		  1.09    0.001328          16        80         3 write
		  1.04    0.001260           2       493         2 read
		  0.90    0.001094           2       495           mmap

Is it possible to recreate a patch to correct this behavior?

Comment 5 RHEL Program Management 2023-09-19 14:01:54 UTC

Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.

Comment 6 RHEL Program Management 2023-09-19 14:04:49 UTC

This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there.

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