| Message ID | 201208021944.q72JiGm2018091@int-mx09.intmail.prod.int.phx2.redhat.com |
|---|---|
| State | New |
| Headers | show |
Jason Baron <jbaron@redhat.com> writes: > Add a new '[,dump-guest-core=on|off]' option to the '-machine' option. When > 'dump-guest-core=off' is specified, guest memory is omitted from the core dump. > The default behavior continues to be to include guest memory when a core dump is > triggered. In my testing, this brought the core dump size down from 384MB to 6MB > on a 2GB guest. > > Is anything additional required to preserve this setting for migration or > savevm? I don't believe so. > > Changelog: > v3: > Eliminate globals as per Anthony's suggestion > set no dump from qemu_ram_remap() as well > v2: > move the option from -m to -machine, rename option dump -> dump-guest-core > > Signed-off-by: Jason Baron <jbaron@redhat.com> > --- > exec.c | 21 +++++++++++++++++++++ > osdep.h | 7 +++++++ > qemu-config.c | 4 ++++ > qemu-options.hx | 5 ++++- > 4 files changed, 36 insertions(+), 1 deletions(-) > > diff --git a/exec.c b/exec.c > index feb4795..4152422 100644 > --- a/exec.c > +++ b/exec.c > @@ -2478,6 +2478,24 @@ static ram_addr_t last_ram_offset(void) > return last; > } > > +static void qemu_ram_setup_dump(void *addr, ram_addr_t size) > +{ > + int ret; > + QemuOpts *machine_opts; > + > + /* Use MADV_DONTDUMP, if user doesn't want the guest memory in the core */ > + machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0); > + if (machine_opts && > + !qemu_opt_get_bool(machine_opts, "dump-guest-core", true)) { > + ret = qemu_madvise(addr, size, QEMU_MADV_DONTDUMP); > + if (ret) { > + perror("qemu_madvise"); > + fprintf(stderr, "madvise doesn't support MADV_DONTDUMP, " > + "but dump_guest_core=off specified\n"); > + } > + } > +} > + > void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev) > { > RAMBlock *new_block, *block; > @@ -2555,6 +2573,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, > last_ram_offset() >> TARGET_PAGE_BITS); > cpu_physical_memory_set_dirty_range(new_block->offset, size, 0xff); > > + qemu_ram_setup_dump(new_block->host, size); > + > if (kvm_enabled()) > kvm_setup_guest_memory(new_block->host, size); > > @@ -2671,6 +2691,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length) > exit(1); > } > qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE); > + qemu_ram_setup_dump(vaddr, length); > } > return; > } > diff --git a/osdep.h b/osdep.h > index 1e15a4b..e2d0f57 100644 > --- a/osdep.h > +++ b/osdep.h > @@ -102,6 +102,11 @@ void qemu_vfree(void *ptr); > #else > #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID > #endif > +#ifdef MADV_DONTDUMP > +#define QEMU_MADV_DONTDUMP MADV_DONTDUMP > +#else > +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID > +#endif > > #elif defined(CONFIG_POSIX_MADVISE) > > @@ -109,6 +114,7 @@ void qemu_vfree(void *ptr); > #define QEMU_MADV_DONTNEED POSIX_MADV_DONTNEED > #define QEMU_MADV_DONTFORK QEMU_MADV_INVALID > #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID > +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID > > #else /* no-op */ > > @@ -116,6 +122,7 @@ void qemu_vfree(void *ptr); > #define QEMU_MADV_DONTNEED QEMU_MADV_INVALID > #define QEMU_MADV_DONTFORK QEMU_MADV_INVALID > #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID > +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID > > #endif > > diff --git a/qemu-config.c b/qemu-config.c > index 5c3296b..6700de0 100644 > --- a/qemu-config.c > +++ b/qemu-config.c > @@ -595,6 +595,10 @@ static QemuOptsList qemu_machine_opts = { > .name = "dt_compatible", > .type = QEMU_OPT_STRING, > .help = "Overrides the \"compatible\" property of the dt root node", > + }, { > + .name = "dump-guest-core", > + .type = QEMU_OPT_BOOL, > + .help = "Include guest memory in a core dump", > }, > { /* End of list */ } > }, > diff --git a/qemu-options.hx b/qemu-options.hx > index dc68e15..a3244d7 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -33,7 +33,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ > " property accel=accel1[:accel2[:...]] selects accelerator\n" > " supported accelerators are kvm, xen, tcg (default: tcg)\n" > " kernel_irqchip=on|off controls accelerated irqchip support\n" > - " kvm_shadow_mem=size of KVM shadow MMU\n", > + " kvm_shadow_mem=size of KVM shadow MMU\n" > + " dump-guest-core=on|off include guest memory in a core dump (default=on)\n", I'd ask you to limit help line length to 80 characters, except there are so many offenders already that one more can't make it worse than it already is. > QEMU_ARCH_ALL) > STEXI > @item -machine [type=]@var{name}[,prop=@var{value}[,...]] > @@ -50,6 +51,8 @@ to initialize. > Enables in-kernel irqchip support for the chosen accelerator when available. > @item kvm_shadow_mem=size > Defines the size of the KVM shadow MMU. > +@item dump-guest-core=on|off > +Include guest memory in a core dump. The default is on. > @end table > ETEXI Looks good to me.
diff --git a/exec.c b/exec.c index feb4795..4152422 100644 --- a/exec.c +++ b/exec.c @@ -2478,6 +2478,24 @@ static ram_addr_t last_ram_offset(void) return last; } +static void qemu_ram_setup_dump(void *addr, ram_addr_t size) +{ + int ret; + QemuOpts *machine_opts; + + /* Use MADV_DONTDUMP, if user doesn't want the guest memory in the core */ + machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0); + if (machine_opts && + !qemu_opt_get_bool(machine_opts, "dump-guest-core", true)) { + ret = qemu_madvise(addr, size, QEMU_MADV_DONTDUMP); + if (ret) { + perror("qemu_madvise"); + fprintf(stderr, "madvise doesn't support MADV_DONTDUMP, " + "but dump_guest_core=off specified\n"); + } + } +} + void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev) { RAMBlock *new_block, *block; @@ -2555,6 +2573,8 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, last_ram_offset() >> TARGET_PAGE_BITS); cpu_physical_memory_set_dirty_range(new_block->offset, size, 0xff); + qemu_ram_setup_dump(new_block->host, size); + if (kvm_enabled()) kvm_setup_guest_memory(new_block->host, size); @@ -2671,6 +2691,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length) exit(1); } qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE); + qemu_ram_setup_dump(vaddr, length); } return; } diff --git a/osdep.h b/osdep.h index 1e15a4b..e2d0f57 100644 --- a/osdep.h +++ b/osdep.h @@ -102,6 +102,11 @@ void qemu_vfree(void *ptr); #else #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID #endif +#ifdef MADV_DONTDUMP +#define QEMU_MADV_DONTDUMP MADV_DONTDUMP +#else +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID +#endif #elif defined(CONFIG_POSIX_MADVISE) @@ -109,6 +114,7 @@ void qemu_vfree(void *ptr); #define QEMU_MADV_DONTNEED POSIX_MADV_DONTNEED #define QEMU_MADV_DONTFORK QEMU_MADV_INVALID #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID #else /* no-op */ @@ -116,6 +122,7 @@ void qemu_vfree(void *ptr); #define QEMU_MADV_DONTNEED QEMU_MADV_INVALID #define QEMU_MADV_DONTFORK QEMU_MADV_INVALID #define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID +#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID #endif diff --git a/qemu-config.c b/qemu-config.c index 5c3296b..6700de0 100644 --- a/qemu-config.c +++ b/qemu-config.c @@ -595,6 +595,10 @@ static QemuOptsList qemu_machine_opts = { .name = "dt_compatible", .type = QEMU_OPT_STRING, .help = "Overrides the \"compatible\" property of the dt root node", + }, { + .name = "dump-guest-core", + .type = QEMU_OPT_BOOL, + .help = "Include guest memory in a core dump", }, { /* End of list */ } }, diff --git a/qemu-options.hx b/qemu-options.hx index dc68e15..a3244d7 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -33,7 +33,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ " property accel=accel1[:accel2[:...]] selects accelerator\n" " supported accelerators are kvm, xen, tcg (default: tcg)\n" " kernel_irqchip=on|off controls accelerated irqchip support\n" - " kvm_shadow_mem=size of KVM shadow MMU\n", + " kvm_shadow_mem=size of KVM shadow MMU\n" + " dump-guest-core=on|off include guest memory in a core dump (default=on)\n", QEMU_ARCH_ALL) STEXI @item -machine [type=]@var{name}[,prop=@var{value}[,...]] @@ -50,6 +51,8 @@ to initialize. Enables in-kernel irqchip support for the chosen accelerator when available. @item kvm_shadow_mem=size Defines the size of the KVM shadow MMU. +@item dump-guest-core=on|off +Include guest memory in a core dump. The default is on. @end table ETEXI
Add a new '[,dump-guest-core=on|off]' option to the '-machine' option. When 'dump-guest-core=off' is specified, guest memory is omitted from the core dump. The default behavior continues to be to include guest memory when a core dump is triggered. In my testing, this brought the core dump size down from 384MB to 6MB on a 2GB guest. Is anything additional required to preserve this setting for migration or savevm? I don't believe so. Changelog: v3: Eliminate globals as per Anthony's suggestion set no dump from qemu_ram_remap() as well v2: move the option from -m to -machine, rename option dump -> dump-guest-core Signed-off-by: Jason Baron <jbaron@redhat.com> --- exec.c | 21 +++++++++++++++++++++ osdep.h | 7 +++++++ qemu-config.c | 4 ++++ qemu-options.hx | 5 ++++- 4 files changed, 36 insertions(+), 1 deletions(-)