> -----Original Message----- > From: Venkatesh Srinivas [mailto:venkateshs@xxxxxxxxxx] > Sent: Monday, March 23, 2015 5:23 PM > To: KY Srinivasan > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; Linux Kernel Developers List; > devel@xxxxxxxxxxxxxxxxxxxxxx; ohering@xxxxxxxx; James E.J. Bottomley; > Christoph Hellwig; linux-scsi@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; > vkuznets@xxxxxxxxxx; jasowang@xxxxxxxxxx > Subject: Re: [PATCH RESEND 2/7] scsi: storvsc: Size the queue depth based > on the ringbuffer size > > On Mon, Mar 23, 2015 at 2:06 PM, K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > wrote: > > Size the queue depth based on the ringbuffer size. Also accomodate for > the > > fact that we could have multiple channels (ringbuffers) per adaptor. > > > > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > Reviewed-by: Long Li <longli@xxxxxxxxxxxxx> > > --- > > drivers/scsi/storvsc_drv.c | 27 ++++++++++++++++----------- > > 1 files changed, 16 insertions(+), 11 deletions(-) > > > > diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c > > index 27fe850..5a12897 100644 > > --- a/drivers/scsi/storvsc_drv.c > > +++ b/drivers/scsi/storvsc_drv.c > > @@ -309,10 +309,15 @@ enum storvsc_request_type { > > */ > > > > static int storvsc_ringbuffer_size = (256 * PAGE_SIZE); > > +static u32 max_outstanding_req_per_channel; > > + > > +static int storvsc_vcpus_per_sub_channel = 4; > > > > module_param(storvsc_ringbuffer_size, int, S_IRUGO); > > MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size > (bytes)"); > > > > +module_param(storvsc_vcpus_per_sub_channel, int, S_IRUGO); > > +MODULE_PARM_DESC(vcpus_per_sub_channel, "Ratio of VCPUs to > subchannels"); > > /* > > * Timeout in seconds for all devices managed by this driver. > > */ > > @@ -320,7 +325,6 @@ static int storvsc_timeout = 180; > > > > static int msft_blist_flags = BLIST_TRY_VPD_PAGES; > > > > -#define STORVSC_MAX_IO_REQUESTS 200 > > > > static void storvsc_on_channel_callback(void *context); > > > > @@ -1376,7 +1380,6 @@ static int storvsc_do_io(struct hv_device *device, > > > > static int storvsc_device_configure(struct scsi_device *sdevice) > > { > > - scsi_change_queue_depth(sdevice, STORVSC_MAX_IO_REQUESTS); > > > > blk_queue_max_segment_size(sdevice->request_queue, > PAGE_SIZE); > > > > @@ -1646,7 +1649,6 @@ static struct scsi_host_template scsi_driver = { > > .eh_timed_out = storvsc_eh_timed_out, > > .slave_configure = storvsc_device_configure, > > .cmd_per_lun = 255, > > - .can_queue = > STORVSC_MAX_IO_REQUESTS*STORVSC_MAX_TARGETS, > > .this_id = -1, > > /* no use setting to 0 since ll_blk_rw reset it to 1 */ > > /* currently 32 */ > > @@ -1686,6 +1688,7 @@ static int storvsc_probe(struct hv_device *device, > > const struct hv_vmbus_device_id *dev_id) > > { > > int ret; > > + int num_cpus = num_online_cpus(); > > struct Scsi_Host *host; > > struct hv_host_device *host_dev; > > bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false); > > @@ -1694,6 +1697,7 @@ static int storvsc_probe(struct hv_device *device, > > int max_luns_per_target; > > int max_targets; > > int max_channels; > > + int max_sub_channels = 0; > > > > /* > > * Based on the windows host we are running on, > > @@ -1719,12 +1723,18 @@ static int storvsc_probe(struct hv_device > *device, > > max_luns_per_target = STORVSC_MAX_LUNS_PER_TARGET; > > max_targets = STORVSC_MAX_TARGETS; > > max_channels = STORVSC_MAX_CHANNELS; > > + /* > > + * On Windows8 and above, we support sub-channels for storage. > > + * The number of sub-channels offerred is based on the number > of > > + * VCPUs in the guest. > > + */ > > + max_sub_channels = (num_cpus / > storvsc_vcpus_per_sub_channel); > > break; > > } > > > > - if (dev_id->driver_data == SFC_GUID) > > - scsi_driver.can_queue = (STORVSC_MAX_IO_REQUESTS * > > - STORVSC_FC_MAX_TARGETS); > > + scsi_driver.can_queue = (max_outstanding_req_per_channel * > > + max_sub_channels + 1); > > + > > If num_online_cpus() returned 1 - 3, can_queue will be set to 1 I > think. Is that desired? can_ queue will be set max_outstanding_req_per_channel in this case. That is what is expected. We will always have the primary channel; Additionally, if the guest has more than 4 VCPUs, the host will offer Additional subchannels for each 4 VCPus in the guest. So for less than 4 VCPus in the guest, we will only have the primary channel. Regards, K. Y ��.n��������+%������w��{.n�����{������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
