#10180 NORM 1.5-sof: Journal hangs every five or six entry erasures

[Zarro Boogs per Child]

#10180: Journal hangs every five or six entry erasures
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           Reporter:  Quozl             |       Owner:  tomeu                            
               Type:  defect            |      Status:  new                              
           Priority:  normal            |   Milestone:  1.5-software-later               
          Component:  journal-activity  |     Version:  Development build as of this date
         Resolution:                    |    Keywords:                                   
        Next_action:  diagnose          |    Verified:  0                                
Deployment_affected:                    |   Blockedby:                                   
           Blocking:                    |  
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Comment(by tomeu):

 Replying to [comment:1 Quozl]:
 > Diagnosis ... the stall corresponds to an unlink(2) call made by the
 datastore service.
 >
 > {{{
 > 02:54:15.303495
 unlink("/home/olpc/.sugar/default/datastore/checksums/65033cfd0f41ac47b09e9f20c3bec62b/91491990-
 5bd-42f0-8d79-093f63aa5534") = 0
 > 02:54:21.379574
 stat64("/home/olpc/.sugar/default/datastore/checksums/65033cfd0f41ac47b09e9f20c3bec62b",
 {st_mod =S_IFDIR|0755, st_size=4096, ...}) = 0
 > }}}
 >
 > So the stall is probably unavoidable in the current design of Sugar ...

 Cannot be improved in the lower layers?

 > this is a design problem in the Journal activity.

 If by design you mean that these operations could be done async but aren't
 currently, then yes. But making that change wouldn't mean too much work.

 The current Journal and DS were tested on a XO-1 and the performance of
 these operations was never so slow.

 Just to be clear, every I/O operation should be done async if we want an
 UI as responsive as possible, but it has a cost in development and you
 need to expose the pending operations in the UI along with any errors,
 eventual completion message, etc.

-- 
Ticket URL: <http://dev.laptop.org/ticket/10180#comment:3>
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