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Bug 154432

Summary: kernel dm-multipath uses default workqueue but sleeps causing other users problems
Product: Red Hat Enterprise Linux 4 Reporter: Alasdair Kergon <agk>
Component: kernelAssignee: Alasdair Kergon <agk>
Status: CLOSED NEXTRELEASE QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: 4.2CC: agk, christophe.varoqui, dmo, lmb, tranlan
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2005-11-15 18:11:19 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Attachments:
Description Flags
Separate workqueue for dm-mpath.c in kernel 2.6.5
none
Updated separate workqueue patch (against 2.6.5-SLES, but based on the latest DM patchset) none

Description Alasdair Kergon 2005-04-11 17:23:51 UTC
Get a lot of IO to fail on the same dm multipath device and continue to
send new IO, so that the underlying device queue hits the nr_request and
batching limits and ends up blocking.
                                                                               
                                                     
If the generic_make_request call that ends up blocking comes from
dm-mpath.c's dispatch_failed_ios() then it will end up blocking all the
users of the default workqueue on that processor.
                                                                               
                                                     
A simple fix would be to just have dm-multipath use its own workqueue,
which is what the other device-mapper targets do to avoid the problem.

[From Mike Christie (IBM) via Suse]

Comment 1 Alasdair Kergon 2005-04-11 17:23:51 UTC
Created attachment 112957 [details]
Separate workqueue for dm-mpath.c in kernel 2.6.5

Comment 2 Lars Marowsky-Bree 2005-04-20 09:53:33 UTC
Created attachment 113400 [details]
Updated separate workqueue patch (against 2.6.5-SLES, but based on the latest DM patchset)

Comment 3 Alasdair Kergon 2005-04-21 16:59:30 UTC
Adding to 2.6.12-rc2-udm1

Comment 4 Alasdair Kergon 2005-11-15 18:11:19 UTC
upstream and in RHEL