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 Boaz --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
