Messages in this thread | | | Date | Fri, 29 Aug 2014 14:16:47 -0500 | From | Mike Travis <> | Subject | [PATCH 0/2] x86: Speed up ioremap operations |
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We have a large university system in the UK that is experiencing very long delays modprobing the driver for a specific I/O device. The delay is from 8-10 minutes per device and there are 31 devices in the system. This 4 to 5 hour delay in starting up those I/O devices is very much a burden on the customer.
There are two causes for requiring a restart/reload of the drivers. First is periodic preventive maintenance (PM) and the second is if any of the devices experience a fatal error. Both of these trigger this excessively long delay in bringing the system back up to full capability.
The problem was tracked down to a very slow IOREMAP operation and the excessively long ioresource lookup to insure that the user is not attempting to ioremap RAM. These patches provide a speed up to that function.
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