On 02/06/2017 10:59 AM, Shivasharan S wrote: > Avoid Host side PCI bandwidth bottleneck and hint FW to do Write buffering using > RaidFlag MR_RAID_FLAGS_IO_SUB_TYPE_LDIO_BW_LIMIT. > Once IO is landed in FW with MR_RAID_FLAGS_IO_SUB_TYPE_LDIO_BW_LIMIT, > it will do single DMA from host and buffer the Write operation. On back end, > FW will DMA same buffer to the Mirror and Data Arm. > This will improve large block IO performance which bottleneck due to Host side PCI bandwidth limitation. > > Consistent ~4000MB T.P for 256K Block size is expected performance numbers. > IOPS for small Block size should be on par with Disk performance. > (E.g 42 SAS Disk in JBOD mode gives 3700MB T.P. > Same Drive used in R1 WT mode, should give ~1800MB T.P) > > Using this patch 24 R1 VDs (HDD) gives below performance for Sequential Write. > Without this patch, we cannot reach above 3200MB (Throughput is in MB. ) > > Block Size 50% 256K and 50% 4K 100% 256K > 4K 3100 2030 > 8K 3140 2740 > 16K 3140 3140 > 32K 3400 3240 > 64K 3500 3700 > 128K 3870 3870 > 256K 3920 3920 > > Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@xxxxxxxxxxxx> > Signed-off-by: Kashyap Desai <kashyap.desai@xxxxxxxxxxxx> > --- > drivers/scsi/megaraid/megaraid_sas.h | 5 +++++ > drivers/scsi/megaraid/megaraid_sas_fusion.c | 32 +++++++++++++++++++++++++++-- > 2 files changed, 35 insertions(+), 2 deletions(-) > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
