Is this old patch still relevant?
25/07/2018 11:02, Alan Dewar: > Hi Stephen, > > Sorry about the delay in responding to your comment. > > Maybe I'm missing something but I don't consider 64-bit counter > rollover to be a problem. > The DPDK QoS stats are just 32-bits wide and are zeroed when read. So > if we read them frequently enough the 32-bit counters won't wrap. > > This new API is just a convenient way to read the 32-bit counters into > variables that are 64-bit wide which allows Vyatta to have a common > API slightly above the DPDK. > > I'd hope that at some point in time the DPDK will move to 64-bit > counters, but there may be technical reasons why this can't happen > that I'm not aware of (support for 32-bit CPUs??) > > Regards > Alan > > On Mon, Jul 23, 2018 at 5:52 PM, Stephen Hemminger > <step...@networkplumber.org> wrote: > > On Wed, 18 Jul 2018 15:51:39 +0100 > > alangordonde...@gmail.com wrote: > > > >> From: Alan Dewar <alan.de...@att.com> > >> > >> Add new APIs to retrieve counters in 64-bit wide fields. > >> > >> Signed-off-by: Alan Dewar <alan.de...@att.com> > > > > Do you want to consider 64 bit counter roll over on 32 bit platform? > > The problem is that incrementing an 64 bit value is not atomic on > > 32 bit cpu. The carry operation can race with reading. > > > > The kernel has special case code to do restartable sequence for > > accessing 64 bit counter on 32 bit CPU. These functions become > > nop's on 64bit. >
