search for: mmuext

While working on a database scaling problem using a SAP database test suite we discovered that these enterprise level large shared memory databases are very heavy users of mprotect(), to the extent that the performance overhead in current Xenolinux impacts scaling beyond a few cpus quite badly. A single cpu run under Xen has a nominal impact, but scaling out to 8 cpus results in a performance of

...t_valid; } } #endif Index: 2007-03-19/xen/arch/x86/mm.c =================================================================== --- 2007-03-19.orig/xen/arch/x86/mm.c 2007-03-27 10:31:15.000000000 +0200 +++ 2007-03-19/xen/arch/x86/mm.c 2007-03-27 10:32:56.000000000 +0200 @@ -1969,6 +1969,8 @@ int do_mmuext_op( if ( unlikely(!guest_handle_is_null(pdone)) ) (void)copy_from_guest(&done, pdone, 1); } + else + perfc_incr(calls_to_mmuext_op); if ( unlikely(!guest_handle_okay(uops, count)) ) { @@ -2223,6 +2225,8 @@ int do_mmuext_op( UNLOCK_BIGLOCK(...

Hi all, this patch series introduces stolen ticks accounting for Xen on ARM. Stolen ticks are clocksource ticks that have been "stolen" from the cpu, typically because Linux is running in a virtual machine and the vcpu has been descheduled. To account for these ticks we introduce CONFIG_PARAVIRT and pv_time_ops so that we can make use of: