[Varnish] #38: Fault tree for performance diagnosis

[Varnish]

#38: Fault tree for performance diagnosis
----------------------+-----------------------------------------------------
 Reporter:  phk       |       Owner:  phk
     Type:  defect    |      Status:  new
 Priority:  normal    |   Milestone:     
Component:  varnishd  |     Version:     
 Severity:  normal    |    Keywords:     
----------------------+-----------------------------------------------------
 This is a fault tree we can work through to eliminate theories:

 Lower than expected traffic handling
         Alteon not allocating traffic
         Packet loss
         Packet delay
         TCP/session setup failures or rejections
         Bad Varnish responsetime

 Alteon not allocating traffic
         Bad health-check response time
         Health-check failues
         TCP/session setup failures or rejections
         TCP/session count confusion
         Bad Varnish responsetime

 Bad health-check response time
         Packet loss
         Packet delay
         TCP/session setup failures or rejections
         Bad Varnish responsetime

 Health-check failues
         Packet loss
         Packet delay
         TCP/session setup failures or rejections

 Packet loss
         Alteon interface
         GigE switch
         bge1 interface
         FreeBSD Network stack bugs
         FreeBSD resource starvation

 Packet delay
         Alteon bugs
         Alteon interface
         GigE switch
         bge1 interface
         FreeBSD Network stack bugs
         FreeBSD rate limiting
         FreeBSD resource starvation

 TCP/session setup failures or rejections
         FreeBSD Network stack bugs
         FreeBSD rate limiting
         FreeBSD firewalling
         FreeBSD routing
         FreeBSD resource starvation
         Varnish acceptor bugs
         Varnish acceptor resource starvation

 Bad Varnish responsetime
         varnish acceptor bugs
         varnish response bugs
         varnish lock contention
         varnish resource starvation
         thread library schedule bugs
         FreeBSD rate limiting
         FreeBSD resource startvation (sendfile ?)

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Ticket URL: <http://varnish.projects.linpro.no/ticket/38>
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