Which now leads me to wondering if this is due to the coalescing code. If you can run with coalescing off (as described in my last email) that might be telling.TERRY DONTJE <terry.dontje@oracle.com> wrote:On 11/22/2011 6:59 PM, Lukas Razik wrote:Roland Dreier<roland@purestorage.com> wrote:On Tue, Nov 22, 2011 at 3:05 PM, Lukas Razik<linux@razik.name>wrote:#0 0xfffff8010229ba9c in mca_pml_ob1_send_request_start_copy(sendreq=0xb23200, bml_btl=0xb29050, size=0) at pml_ob1_sendreq.c:551551 hdr->hdr_match.hdr_ctx =sendreq->req_send.req_base.req_comm->c_contextid;(gdb) backtraceIf you can get into gdb here, I guess it would be useful to print the address of hdr->hdr_match.hdr_ctx and sendreq->req_send.req_base.req_comm->c_contextid to see which oneismisaligned. Not sure of the gdb syntax... does it work to just do p&hdr->hdr_match.hdr_ctx and sendreq->req_send.req_base.req p&sendreq->req_send.req_base.req_comm->c_contextidOh, sorry that I didn't do that before... The values are: &hdr->hdr_match.hdr_ctx and sendreq->req_send.req_base.req =(uint16_t *) 0xad7393&sendreq->req_send.req_base.req_comm->c_contextid = (uint32_t*) 0x201c20So hdr_ctx is the bad one... PS: I always don't know the syntax of gdb - hence I use the nice kdbg. *g* http://net.razik.de/linux/T5120/kdbg-openmpi-1.4.4-osu_latency-02.pngCan you get me the value of hdr too. I bet it is an odd value too.You're right! :) The value of hdr you can see in the first screenshot I've sent sent you: http://net.razik.de/linux/T5120/kdbg-openmpi-1.4.4-osu_latency.png It's hdr = (mca_pml_ob1_hdr_t*) 0xad7391