Bug 154432 - kernel dm-multipath uses default workqueue but sleeps causing other users problems
kernel dm-multipath uses default workqueue but sleeps causing other users pro...
Status: CLOSED NEXTRELEASE
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
4.2
All Linux
medium Severity medium
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Assigned To: Alasdair Kergon
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Depends On:
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Reported: 2005-04-11 13:23 EDT by Alasdair Kergon
Modified: 2007-11-30 17:07 EST (History)
5 users (show)

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Doc Type: Bug Fix
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Last Closed: 2005-11-15 13:11:19 EST
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Attachments (Terms of Use)
Separate workqueue for dm-mpath.c in kernel 2.6.5 (1.75 KB, patch)
2005-04-11 13:23 EDT, Alasdair Kergon
no flags Details | Diff
Updated separate workqueue patch (against 2.6.5-SLES, but based on the latest DM patchset) (4.63 KB, patch)
2005-04-20 05:53 EDT, Lars Marowsky-Bree
no flags Details | Diff

  None (edit)
Description Alasdair Kergon 2005-04-11 13:23:51 EDT
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 13:23:51 EDT
Created attachment 112957 [details]
Separate workqueue for dm-mpath.c in kernel 2.6.5
Comment 2 Lars Marowsky-Bree 2005-04-20 05:53:33 EDT
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 12:59:30 EDT
Adding to 2.6.12-rc2-udm1
Comment 4 Alasdair Kergon 2005-11-15 13:11:19 EST
upstream and in RHEL

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