Re: RT wakeup woes in Linux 2.6.31.6 on Mac Mini

From: Alan Cox
Date: Fri Nov 13 2009 - 05:42:06 EST


> trace.13653:kblockd/-65 1dN.. 132us+: blk_rq_map_sg <-scsi_init_sgtable
> trace.13653:kblockd/-65 1dN.. 200us+: blk_rq_map_sg <-scsi_init_sgtable
> trace.13653:kblockd/-65 1dN.. 264us+: ata_tf_to_fis <-ahci_qc_prep
> trace.13653:kblockd/-65 1dN.. 289us+: blk_rq_map_sg <-scsi_init_sgtable
> trace.13653:kblockd/-65 1dN.. 349us+: ata_tf_to_fis <-ahci_qc_prep

Something very weird with your tracing there ata_tf_to_fis simply moves
20 bytes of memory about. It could be you are hitting some kind of
caching effect with the AHCI controller I guess. Certainly looks odd of
itself.

> ...
> trace.6039: pdflush-5162 1d.s. 0us : 5162:120:R + [001]
> 6040: 0:S rxtest
> trace.6039: pdflush-5162 1dN.. 61us+: idle_cpu <-irq_exit
> trace.6039: pdflush-5162 1dN.. 130us!: idle_cpu <-irq_exit
> trace.6039: pdflush-5162 1dN.. 273us!: idle_cpu <-irq_exit

What power management do you have enabled ?
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