> -----Original Message----- > From: Dan Carpenter [mailto:dan.carpen...@oracle.com] > Sent: Friday, December 8, 2017 5:45 AM > To: Stephen Hemminger <step...@networkplumber.org> > Cc: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang > <haiya...@microsoft.com>; Stephen Hemminger > <sthem...@microsoft.com>; de...@linuxdriverproject.org; > net...@vger.kernel.org > Subject: Re: [PATCH net 3/3] hv_netvsc: Fix the default receive buffer size > > On Thu, Dec 07, 2017 at 04:10:55PM -0800, Stephen Hemminger wrote: > > From: Haiyang Zhang <haiya...@microsoft.com> > > > > The intended size is 16 MB, and the default slot size is 1728. > > So, NETVSC_DEFAULT_RX should be 16*1024*1024 / 1728 = 9709. > > > > Fixes: 5023a6db73196 ("netvsc: increase default receive buffer size") > > Signed-off-by: Haiyang Zhang <haiya...@microsoft.com> > > Signed-off-by: Stephen Hemminger <sthem...@microsoft.com> > > --- > > drivers/net/hyperv/netvsc_drv.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/net/hyperv/netvsc_drv.c > > b/drivers/net/hyperv/netvsc_drv.c index dc70de674ca9..edfcde5d3621 > > 100644 > > --- a/drivers/net/hyperv/netvsc_drv.c > > +++ b/drivers/net/hyperv/netvsc_drv.c > > @@ -50,7 +50,7 @@ > > #define NETVSC_MIN_TX_SECTIONS 10 > > #define NETVSC_DEFAULT_TX 192 /* ~1M */ > > #define NETVSC_MIN_RX_SECTIONS 10 /* ~64K */ > > -#define NETVSC_DEFAULT_RX 10485 /* Max ~16M */ > > +#define NETVSC_DEFAULT_RX 9709 /* ~16M */ > > How does this bug look like to the user? Memory corruption? > > It's weird to me reviewing this code that the default sizes are stored in > netvsc_drv.c and the max sizes are stored in hyperv_net.h. > Could we move these to hyperv_net.h? We could write it like: > #define NETVSC_DEFAULT_RX ((16 * 1024 * 1024) / > NETVSC_RECV_SECTION_SIZE) > > 16MB is sort of a weird default because it's larger than the 15MB allowed for > legacy versions, but it's smaller than the 32MB you'd want for the current > versions.
As a tradeoff between traffic burst and latency, we set the default to be 16MB. And this default is reduced automatically for legacy hosts based on the NVSP version in patch 2. I will move the change to hyperv_net.h Thanks, - Haiyang _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
