On 03/27/2013 10:03 AM, Dave Chinner wrote: > On Tue, Mar 26, 2013 at 06:14:30PM +0800, Jeff Liu wrote: >> On 03/12/2013 08:05 PM, Dave Chinner wrote: >>> On Tue, Mar 12, 2013 at 07:56:35PM +0800, Jeff Liu wrote: >>>> More info, 3.7.0 is the oldest kernel on my environment, I ran into the >>>> same problem. >>> >>> Thanks for following up so quickly, Jeff. So the problem is that a >>> new test is tripping over a bug that has been around for a while, >>> not that it is a new regression. >>> >>> OK, so I'll expunge that from my testing for the moment as I don't >>> ahve time to dig in and find out what the cause is right now. If >>> anyone else wants to.... :) >> >> I did some further tests to nail down this issue, just posting the analysis result here, >> it might be of some use when we revising it again. >> >> The disk is formated with Dave's previous comments, i.e. >> mkfs.xfs -f -b size=512 -d agcount=16,su=256k,sw=12 -l su=256k,size=2560b /dev/xxx >> >> First of all, looks this bug stayed in hiding for years since I can reproduce it between upstream >> 3.0 to 3.9.0-rc3, the oldest kernel I have tried is 2.6.39 which has the same problem. > > If you mount 2.6.39 with "-o nodelaylog", does the problem go away? touch file is ok, but create directory still cause the assertion failure. > >> IMHO, looks the major cause is related to the 'sunit' parameter, >> since it would affect the log space unit calculations by >> '2*log->l_mp->m_sb.sb_logsunit' at xlog_ticket_alloc(). However, >> we don't include this factor into consideration at mkfs or mount >> stage, should we take it into account? > > That's what I suspected was the problem. i.e. that the log was too > small for the given configuration. > > The question is this: how much space do we need to reserve. I'm > thinking a minimum of 4*lsu - 2*lsu for the existing CIL context, and > another 2*lsu for any queued ticket waiting for space to come > available. > > I haven't thought a lot about it, though, and I have a little demon > sitting on my shoulder nagging me about specific thresholds whether > they need to play a part in this. e.g. no single transaction can be > larger than half the log; AIL push thresholds of 25% of log space; > background CIL commit threshold of 12.5% of the log... > > So it's not immediately clear to me how much bigger the log needs to > be... I still need some time to understand the space reservation strategy to figure them out. :( Thanks, -Jeff _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
