Messages in this thread | | | Subject | Re: [PATCH 4/6] KVM: selftests: memslot_perf_test: Support variable guest page size | From | Gavin Shan <> | Date | Wed, 19 Oct 2022 08:26:19 +0800 |
| |
On 10/18/22 11:56 PM, Maciej S. Szmigiero wrote: > On 18.10.2022 02:51, Gavin Shan wrote: >> On 10/18/22 8:46 AM, Gavin Shan wrote: >>> On 10/18/22 5:31 AM, Maciej S. Szmigiero wrote: >>>> On 14.10.2022 09:19, Gavin Shan wrote: >>>>> The test case is obviously broken on aarch64 because non-4KB guest >>>>> page size is supported. The guest page size on aarch64 could be 4KB, >>>>> 16KB or 64KB. >>>>> >>>>> This supports variable guest page size, mostly for aarch64. >>>>> >>>>> - The host determines the guest page size when virtual machine is >>>>> created. The value is also passed to guest through the synchronization >>>>> area. >>>>> >>>>> - The number of guest pages are unknown until the virtual machine >>>>> is to be created. So all the related macros are dropped. Instead, >>>>> their values are dynamically calculated based on the guest page >>>>> size. >>>>> >>>>> - The static checks on memory sizes and pages becomes dependent >>>>> on guest page size, which is unknown until the virtual machine >>>>> is about to be created. So all the static checks are converted >>>>> to dynamic checks, done in check_memory_sizes(). >>>>> >>>>> - As the address passed to madvise() should be aligned to host page, >>>>> the size of page chunk is automatically selected, other than one >>>>> page. >>>>> >>>>> - All other changes included in this patch are almost mechanical >>>>> replacing '4096' with 'guest_page_size'. >>>>> >>>>> Signed-off-by: Gavin Shan <gshan@redhat.com> >>>>> --- >>>>> .../testing/selftests/kvm/memslot_perf_test.c | 191 +++++++++++------- >>>>> 1 file changed, 115 insertions(+), 76 deletions(-) >>>>> >>>>> diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c >>>>> index d5aa9148f96f..d587bd952ff9 100644 >>>>> --- a/tools/testing/selftests/kvm/memslot_perf_test.c >>>>> +++ b/tools/testing/selftests/kvm/memslot_perf_test.c > (...) >>>>> @@ -77,8 +61,7 @@ static_assert(MEM_TEST_UNMAP_SIZE_PAGES % >>>>> * for the total size of 25 pages. >>>>> * Hence, the maximum size here is 50 pages. >>>>> */ >>>>> -#define MEM_TEST_MOVE_SIZE_PAGES (50) >>>>> -#define MEM_TEST_MOVE_SIZE (MEM_TEST_MOVE_SIZE_PAGES * 4096) >>>>> +#define MEM_TEST_MOVE_SIZE 0x32000 >>>> >>>> The above number seems less readable than an explicit value of 50 pages. >>>> >>>> In addition to that, it's 50 pages only with 4k page size, so at least >>>> the comment above needs to be updated to reflect this fact. >>>> >>> >>> Yeah, I will change the comments like below in next revision. >>> >>> /* >>> * When running this test with 32k memslots, actually 32763 excluding >>> * the reserved memory slot 0, the memory for each slot is 0x4000 bytes. >>> * The last slot contains 0x19000 bytes memory. Hence, the maximum size >>> * here is 0x32000 bytes. >>> */ >>> >> >> I will replace those numbers with readable ones like below :) >> >> /* >> * When running this test with 32k memslots, actually 32763 excluding >> * the reserved memory slot 0, the memory for each slot is 16KB. The >> * last slot contains 100KB memory with the remaining 84KB. Hence, >> * the maximum size is double of that (200KB) >> */ > > Still, these numbers are for x86, which has KVM_INTERNAL_MEM_SLOTS > defined as 3. > > As far as I can see aarch64 has KVM_INTERNAL_MEM_SLOTS equal to 0, so > this arch has 32766 slot available for the test memory. > > Quick calculations show that this will result in 112 KiB of memory in > the last slot for 4 KiB page size (while for 64 KiB page size the > maximum slot count for this test is 8192 anyway - not counting slot 0). >
It seems your calculation had (512MB+64KB), instead of (512MB+4KB). In this particular patch, we still have (512MB+4KB). How about to change like below in this patch. In next patch, it's adjusted accordingly after we have (512MB+64KB).
(1) In this patch, the comment is changed to as below
/* * We have different number of memory slots, excluding the reserved * memory slot 0, on various architectures and configurations. The * memory size in this test is calculated by doubling the maximal * memory size in last memory slot, with alignment to the largest * supported page size (64KB). * * architecture slots memory-per-slot memory-on-last-slot * -------------------------------------------------------------- * x86-4KB 32763 16KB 100KB * arm64-4KB 32766 16KB 52KB * arm64-64KB 8192 64KB 64KB */ #define MEM_TEST_MOVE_SIZE 0x40000 /* 256KB */
(2) In the next patch, where we have (512MB+64KB) after the various memory sizes are consolidated, It is adjusted accordingly as below.
/* * We have different number of memory slots, excluding the reserved * memory slot 0, on various architectures and configurations. The * memory size in this test is calculated by doubling the maximal * memory size in last memory slot, with alignment to the largest * supported page size (64KB). * * architecture slots memory-per-slot memory-on-last-slot * -------------------------------------------------------------- * x86-4KB 32763 16KB 160KB * arm64-4KB 32766 16KB 112KB * arm64-64KB 8192 64KB 128KB */ #define MEM_TEST_MOVE_SIZE 0x50000 /* 320KB */
Thanks, Gavin
| |