sms@wlv.imsd.contel.com (Steven M. Schultz) (01/17/90)
Subject: Network Device Interrupts Not Counted Index: sys/pdp/net_trap.s 2.10BSD Description: Interrupts from network interfaces are not counted if metering (UCB_METER) is selected at system configuration time. Repeat-By: Either by examination of the code, or by performing an rlogin to/from a 2.10.XBSD system and running 'vmstat' on another terminal. Fix: Since the interrupt count is in kernel space, the count must be retrieved via "mfpd" and put back with "mtpd". By performing the increment after the PSW has been loaded with 040340 the overhead of counting interrupts is reduced to only two instructions. Apply the following patch to /sys/pdp/net_trap.s and if UCB_METER is being used, recompile the kernel and networking. *** net_trap.s.old Tue Jul 5 14:20:04 1988 --- net_trap.s Tue Jan 16 21:05:51 1990 *************** *** 33,42 **** * from kernel mode to the PS, PC pair we push on the kernel stack. * * Transfer our saved <PS, PC> pair to the kernel stack. The spl7 ! * below is pure paranoia. */ mov PS,-(sp) mov $40340,PS / current mode SUPV, prev KERN, BR7 mfpd sp / old kernel stack pointer mov (sp),r1 sub $4,(sp) / grow the kernel stack --- 33,49 ---- * from kernel mode to the PS, PC pair we push on the kernel stack. * * Transfer our saved <PS, PC> pair to the kernel stack. The spl7 ! * below is pure paranoia, BUT while we're at it let's bump the ! * interrupt count - it's a mere two instructions of overhead (the ! * increment would have been done anyhow)! */ mov PS,-(sp) mov $40340,PS / current mode SUPV, prev KERN, BR7 + #ifdef UCB_METER + mfpd *$_cnt+V_INTR / fetch interrupt count + inc (sp) / bump it + mtpd *$_cnt+V_INTR / put it back + #endif mfpd sp / old kernel stack pointer mov (sp),r1 sub $4,(sp) / grow the kernel stack