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cb83ba8c1a
virtio-mem logically plugs/unplugs memory within a sparse memory region and notifies via the RamDiscardManager interface when parts become plugged (populated) or unplugged (discarded). Currently, we end up (via the two users) 1) zeroing all logically unplugged/discarded memory during TPM resets. 2) reading all logically unplugged/discarded memory when dumping, to figure out the content is zero. 1) is always bad, because we assume unplugged memory stays discarded (and is already implicitly zero). 2) isn't that bad with anonymous memory, we end up reading the zero page (slow and unnecessary, though). However, once we use some file-backed memory (future use case), even reading will populate memory. Let's cut out all parts marked as not-populated (discarded) via the RamDiscardManager. As virtio-mem is the single user, this now means that logically unplugged memory ranges will no longer be included in the dump, which results in smaller dump files and faster dumping. virtio-mem has a minimum granularity of 1 MiB (and the default is usually 2 MiB). Theoretically, we can see quite some fragmentation, in practice we won't have it completely fragmented in 1 MiB pieces. Still, we might end up with many physical ranges. Both, the ELF format and kdump seem to be ready to support many individual ranges (e.g., for ELF it seems to be UINT32_MAX, kdump has a linear bitmap). Reviewed-by: Peter Xu <peterx@redhat.com> Cc: Marc-André Lureau <marcandre.lureau@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Claudio Fontana <cfontana@suse.de> Cc: Thomas Huth <thuth@redhat.com> Cc: "Alex Bennée" <alex.bennee@linaro.org> Cc: Peter Xu <peterx@redhat.com> Cc: Laurent Vivier <lvivier@redhat.com> Cc: Stefan Berger <stefanb@linux.ibm.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20210727082545.17934-5-david@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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| .. | ||
| arch_init.c | ||
| balloon.c | ||
| bootdevice.c | ||
| cpu-throttle.c | ||
| cpu-timers.c | ||
| cpus.c | ||
| datadir.c | ||
| device_tree.c | ||
| dma-helpers.c | ||
| globals.c | ||
| icount.c | ||
| ioport.c | ||
| main.c | ||
| memory.c | ||
| memory_mapping.c | ||
| meson.build | ||
| physmem.c | ||
| qdev-monitor.c | ||
| qemu-seccomp.c | ||
| qtest.c | ||
| rtc.c | ||
| runstate-action.c | ||
| runstate.c | ||
| timers-state.h | ||
| tpm.c | ||
| trace-events | ||
| trace.h | ||
| vl.c | ||