| Message ID | 20241029202041.25334-3-gourry@gourry.net |
|---|---|
| State | Superseded |
| Headers | show |
| Series | memory,x86,acpi: hotplug memory alignment advisement | expand |
On 29.10.24 21:20, Gregory Price wrote: > Systems with hotplug may provide an advisement value on what the > memblock size should be. Probe this value when the rest of the > configuration values are considered. > > The new heuristic is as follows > > 1) set_memory_block_size_order value if already set (cmdline param) > 2) minimum block size if memory is less than large block limit > 3) if no hotplug advice: Max block size if system is bare-metal, > otherwise use end of memory alignment. > 4) if hotplug advice: lesser of advice and end of memory alignment. > > Suggested-by: David Hildenbrand <david@redhat.com> > Signed-off-by: Gregory Price <gourry@gourry.net> > Acked-by: David Hildenbrand <david@redhat.com> > --- > arch/x86/mm/init_64.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index ff253648706f..01876629f21f 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1452,16 +1452,20 @@ static unsigned long probe_memory_block_size(void) > } > > /* > - * Use max block size to minimize overhead on bare metal, where > - * alignment for memory hotplug isn't a concern. > + * When hotplug alignment is not a concern, maximize blocksize > + * to minimize overhead. Otherwise, align to the lesser of advice > + * alignment and end of memory alignment. > */ > - if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) { > + bz = memory_block_advised_max_size(); > + if (!bz) { > bz = MAX_BLOCK_SIZE; > - goto done; > - } > + if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) > + goto done; > + } else > + bz = max(min(bz, MAX_BLOCK_SIZE), MIN_MEMORY_BLOCK_SIZE); Nit: coding style want you to use if () { } else { }
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index ff253648706f..01876629f21f 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1452,16 +1452,20 @@ static unsigned long probe_memory_block_size(void) } /* - * Use max block size to minimize overhead on bare metal, where - * alignment for memory hotplug isn't a concern. + * When hotplug alignment is not a concern, maximize blocksize + * to minimize overhead. Otherwise, align to the lesser of advice + * alignment and end of memory alignment. */ - if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) { + bz = memory_block_advised_max_size(); + if (!bz) { bz = MAX_BLOCK_SIZE; - goto done; - } + if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) + goto done; + } else + bz = max(min(bz, MAX_BLOCK_SIZE), MIN_MEMORY_BLOCK_SIZE); /* Find the largest allowed block size that aligns to memory end */ - for (bz = MAX_BLOCK_SIZE; bz > MIN_MEMORY_BLOCK_SIZE; bz >>= 1) { + for (; bz > MIN_MEMORY_BLOCK_SIZE; bz >>= 1) { if (IS_ALIGNED(boot_mem_end, bz)) break; }