On Thu, May 07, 2009 at 01:44:38PM +0300, Avi Kivity wrote: > I imagine this loop is present in many drivers. So why not add a helper Let's look! arch/x86/kernel/amd_iommu_init.c : Needs an exact number of vectors. drivers/block/cciss.c : If it doesn't get all 4 vectors, falls back to pin mode (instead of MSI mode -- bug!) drivers/dma/ioat_dma.c : Falls back down to 1 vector if it can't get nvec drivers/infiniband/hw/mthca/mthca_main.c : Reverts to MSI if it can't get 3. drivers/net/benet/be_main.c : Falls back to MSI if it can't get 2. drivers/net/bnx2.c : Falls back to MSI if it can't get 9. drivers/net/bnx2x_main.c : Falls back to MSI if it can't get N. drivers/net/e1000e/netdev.c: Falls back to MSI if it can't get N. drivers/net/enic/enic_main.c: Falls back to MSI if it can't get N. drivers/net/forcedeth.c: Falls back to MSI if it can't get N. drivers/net/igb/igb_main.c: Falls back to MSI if it can't get N. drivers/net/igbvf/netdev.c: Falls back to MSI if it can't get 3. drivers/net/myri10ge/myri10ge.c: Falls back to Pin if it can't get N. drivers/net/netxen/netxen_nic_main.c: Falls back to MSI if it can't get N. drivers/net/qlge/qlge_main.c: Falls back to MSI if it can't get N. drivers/net/s2io.c: Falls back to MSI if it can't get N. drivers/net/vxge/vxge-main.c: Falls back once to a second number. drivers/pci/pcie/portdrv_core.c: Falls back to MSI if it can't get all of them. drivers/scsi/lpfc/lpfc_init.c: Falls back to MSI if it can't get N. drivers/scsi/mpt2sas/mpt2sas_base.c: Only allocates 1. drivers/net/cxgb3/cxgb3_main.c: Actually falls back ... in a bit of a weird way. This one could definitely do with the proposed loop. drivers/net/ixgbe/ixgbe_main.c: Could also be improved with this loop. drivers/net/mlx4/main.c: Nasty goto-based loop. drivers/net/niu.c: Ditto drivers/net/sfc/efx.c: Only falls back once. Would benefit from loop. drivers/scsi/qla2xxx/qla_isr.c: Only falls back once. Would benefit from loop. drivers/staging/sxg/sxg.c: /*Should try with less vector returned.*/ so ... 7 drivers would benefit from this loop. 20 seem like they wouldn't. What a lot of drivers seem to do is fall back either to a single MSI or just pin-based interrupts when they can't get as many interrupts as they would like. They don't try to get a single MSI-X interrupt. I feel an update to the MSI-HOWTO coming on. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
