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| author | Igor Mammedov <imammedo@redhat.com> | 2025-08-14 18:05:53 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2025-08-29 12:48:14 +0200 |
| commit | 73c520b088878682e2d3b7fa19a6366ec8d39829 (patch) | |
| tree | 4766e598cc92df2e3f4c565ff3e451e2f215ea04 /include | |
| parent | 87511341c30d8c9c77178db16491a0ccacc5d64b (diff) | |
| download | focaccia-qemu-73c520b088878682e2d3b7fa19a6366ec8d39829.tar.gz focaccia-qemu-73c520b088878682e2d3b7fa19a6366ec8d39829.zip | |
memory: reintroduce BQL-free fine-grained PIO/MMIO
This patch brings back Jan's idea [1] of BQL-free IO access This will let us make access to ACPI PM/HPET timers cheaper, and prevent BQL contention in case of workload that heavily uses the timers with a lot of vCPUs. 1) 196ea13104f (memory: Add global-locking property to memory regions) ... de7ea885c539 (kvm: Switch to unlocked MMIO) Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Link: https://lore.kernel.org/r/20250814160600.2327672-2-imammedo@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/system/memory.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/system/memory.h b/include/system/memory.h index e2cd6ed126..aa85fc27a1 100644 --- a/include/system/memory.h +++ b/include/system/memory.h @@ -833,6 +833,7 @@ struct MemoryRegion { bool nonvolatile; bool rom_device; bool flush_coalesced_mmio; + bool lockless_io; bool unmergeable; uint8_t dirty_log_mask; bool is_iommu; @@ -2342,6 +2343,17 @@ void memory_region_set_flush_coalesced(MemoryRegion *mr); void memory_region_clear_flush_coalesced(MemoryRegion *mr); /** + * memory_region_enable_lockless_io: Enable lockless (BQL free) acceess. + * + * Enable BQL-free access for devices that are well prepared to handle + * locking during I/O themselves: either by doing fine grained locking or + * by providing lock-free I/O schemes. + * + * @mr: the memory region to be updated. + */ +void memory_region_enable_lockless_io(MemoryRegion *mr); + +/** * memory_region_add_eventfd: Request an eventfd to be triggered when a word * is written to a location. * |