Richard, I remember that default dma boundary was 512 byte earlier sometime 2.6.30 kernel version. Later kernel has introduced 4 byte dma boundary in scsi_lib.c.... As I have mentioned we have limitation of single sgl for ATA PIO commands. So making 512 byte dma boundary will solve all functional issue, but As mentioned in bugzilla #25, people are seeing performance degradation (may due to bounce buffer usage). I need to debug that part. In my opinion if setting "dma boundary to 512 byte is a solution only if there is no performance degradation" Can I have data how user at bugzilla is testing performance? Thanks, Kashyap > -----Original Message----- > From: Richard Scobie [mailto:richard@xxxxxxxxxxx] > Sent: Friday, June 04, 2010 1:38 AM > To: linux-scsi@xxxxxxxxxxxxxxx > Cc: Desai, Kashyap > Subject: RE: mptsas hangs caused by ATA pass-through explained > > Kashyap wrote: > > I have also verified this patch + also done code review with our > developers including Eric Moore. Please consider this patch as an ACKed > patch and schedule it for next upstream release. > > ---------------------- > > Hi, > > In comment #20 of this bug entry: > > https://bugzilla.kernel.org/show_bug.cgi?id=14831 > > you state: > > "Patch for setting dma boundary is mere avoiding condition which is > causing this > issue. LSI Gen-1 controller does not have 512byte dma boundary > limitation. I > have started internal chat with our Firmware engineer. I will update > you > findings as and when some imp stuffs are found." > > Is this still the case, or is the patch the final fix? > > Also, comment #25 in the same thread notes a significant negative write > performance impact. > > Are you seeing this? > > I have several machines in production I would like to update, but not > if > there is a better solution to this on it's way. > > Regards, > > Richard -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
