On Wed, Feb 18, 2009 at 10:09 PM, Boaz Harrosh <bharr...@panasas.com> wrote: > > Mike Christie wrote: >> Erez Zilber wrote: >>> On Tue, Feb 17, 2009 at 11:35 PM, Mike Christie <micha...@cs.wisc.edu> >>> wrote: >>>> Erez Zilber wrote: >>>>> Hi, >>>>> >>>>> I'm running a setup of open-iscsi connected to a target. When I run >>>>> I/O from the initiator (e.g using dd) with transaction size of 128kB, >>>>> I sometimes see that 2 128kB requests are aggregated to a single 256kB >>>>> request. This is rare, but it happens from time to time. Can I disable >>>>> this feature? Who is responsible for that? Is it scsi-ml? >>>>> >>>> block layer. >>>> >>>> /sys/block/sdX/queue/max_sectors_kb >>> Thanks, but this will limit the I/O size for all I/Os. What I forgot >>> to mention is that sometimes I also send larger I/Os (e.g. 512kB). >>> With the proposed solution, these large I/Os will be sent as multiple >>> 128kB I/Os (and affect the performance). Isn't there a way to simply >>> avoid this aggregation? >>> >> >> Not that I know of when going through the block layer. I think you will >> have to ask lkml. >> >> I think the only way to control it is the bsg/sg/passthrough route >> since that does not do merging. The other alternative is to just hack >> the code to do what you want :) >> > > You can select the no-op I/O elevator and you can also use direct IO > like with sg_dd from the sg_utils package >
I'm using noop already, but that didn't help. I'll try to ask in lkml. Thanks, Erez --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "open-iscsi" group. To post to this group, send email to open-iscsi@googlegroups.com To unsubscribe from this group, send email to open-iscsi+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/open-iscsi -~----------~----~----~----~------~----~------~--~---
