On Sunday, March 29, 2020 at 10:04:45 AM UTC-4, Nadav Har'El wrote: > > Looks very good, I have several minor suggestions below (inline), but I > would have committed this patch anyway, > except that I didn't understand is why this patch is titled "2/2" - where > is 1/2? I couldn't find it. > It is called '[PATCH V2 1/2] mempool: fix a bug in page_range_allocator() when handling worst case O(n) scenario' from Match 24th. It fixes somewhat related bug.
> > I see you have new realloc() tests - did these tests fail before your > patches? > I think one of the previous version of this patch was failing and in any case, it was a way for me to better verify my changes, > > -- > Nadav Har'El > [email protected] <javascript:> > > > On Thu, Mar 26, 2020 at 8:36 PM Waldemar Kozaczuk <[email protected] > <javascript:>> wrote: > >> This patch mostly addresses the issue #854. In essence it changes >> malloc_large() >> to use mmu::map_anon() if requested memory is greater than size of "huge >> page" >> and it does not have be contiguous in physical memory. Also it makes it >> fallback >> to map_anon() based allocation for requests > 4K and < 2MB that cannot be >> satisfied >> when memory is heavily fragmented. >> >> It is supposed to help OSv memory allocation behave better when memory >> in free_page_ranges is heavily fragmented and large allocations (>=2MB) >> cannot be satisfied with single contiguous page range. When working on >> this patch it has also become clear, that applications that heavily use >> realloc() >> which allocates new chunks of memory and frees old ones, might very much >> encounter >> heavy fragmentation of memory. Hopefully this patch is going to help >> in these scenarios. >> >> It just happens that object_size() and large_object_size() needed to be >> adjusted to work with new malloc_large() implementation. It was discovered >> that therefore other related issues are fixed by this patch as well. >> >> Fixes #854 >> Fixed #1077 >> >> This patch also potentially addresses realloc() related issue #784. >> > > It seems very likely it does address this as well. Maybe we should just > close this issue too, because we're never going to get more information > about this issue. > > >> Lastly this patch adds new test verifying realloc() and >> malloc_usable_size(). >> >> Signed-off-by: Waldemar Kozaczuk <[email protected] <javascript:>> >> --- >> core/mempool.cc | 66 +++++++++++++++++++++++------ >> modules/tests/Makefile | 2 +- >> tests/tst-realloc.cc | 94 ++++++++++++++++++++++++++++++++++++++++++ >> 3 files changed, 149 insertions(+), 13 deletions(-) >> create mode 100644 tests/tst-realloc.cc >> >> diff --git a/core/mempool.cc b/core/mempool.cc >> index 11fd1456..1bf010d6 100644 >> --- a/core/mempool.cc >> +++ b/core/mempool.cc >> @@ -546,7 +546,7 @@ public: >> page_range_allocator() : _deferred_free(nullptr) { } >> >> template<bool UseBitmap = true> >> - page_range* alloc(size_t size); >> + page_range* alloc(size_t size, bool contiguous = true); >> page_range* alloc_aligned(size_t size, size_t offset, size_t >> alignment, >> bool fill = false); >> void free(page_range* pr); >> @@ -678,7 +678,7 @@ void >> page_range_allocator::bitmap_allocator<T>::deallocate(T* p, size_t n) >> } >> >> template<bool UseBitmap> >> -page_range* page_range_allocator::alloc(size_t size) >> +page_range* page_range_allocator::alloc(size_t size, bool contiguous) >> { >> auto exact_order = ilog2_roundup(size / page_size); >> if (exact_order > max_order) { >> @@ -692,13 +692,12 @@ page_range* page_range_allocator::alloc(size_t size) >> >> page_range* range = nullptr; >> if (!bitset) { >> - if (!exact_order || _free[exact_order - 1].empty()) { >> + if (!contiguous || !exact_order || _free[exact_order - >> 1].empty()) { >> return nullptr; >> } >> - // TODO: This linear search makes worst case complexity of the >> allocator >> - // O(n). It would be better to fall back to non-contiguous >> allocation >> - // and make worst case complexity depend on the size of >> requested memory >> - // block and the logarithm of the number of free huge page >> ranges. >> + // This linear search makes worst case complexity of the >> allocator >> + // O(n). Unfortunately we do not have choice for contiguous >> allocation >> + // so let us hope there is large enough range. >> for (auto&& pr : _free[exact_order - 1]) { >> if (pr.size >= size) { >> range = ≺ >> @@ -823,7 +822,16 @@ void page_range_allocator::for_each(unsigned >> min_order, Func f) >> } >> } >> >> -static void* malloc_large(size_t size, size_t alignment, bool block = >> true) >> +static void* mapped_malloc_large(size_t size, size_t offset) >> +{ >> + //TODO: For now pre-populate the memory, in future consider doing >> lazy population >> + void* obj = mmu::map_anon(nullptr, size, mmu::mmap_populate, >> mmu::perm_read | mmu::perm_write); >> + size_t* ret_header = static_cast<size_t*>(obj); >> + *ret_header = size; >> + return obj + offset; >> +} >> + >> +static void* malloc_large(size_t size, size_t alignment, bool block = >> true, bool contiguous = true) >> { >> auto requested_size = size; >> size_t offset; >> @@ -835,6 +843,14 @@ static void* malloc_large(size_t size, size_t >> alignment, bool block = true) >> size += offset; >> size = align_up(size, page_size); >> >> + // Use mmap if requested memory greater than "huge page" size >> + // and does not need to be contiguous >> + if (size >= mmu::huge_page_size && !contiguous) { >> + void* obj = mapped_malloc_large(size, offset); >> + trace_memory_malloc_large(obj, requested_size, size, alignment); >> + return obj; >> + } >> + >> while (true) { >> WITH_LOCK(free_page_ranges_lock) { >> reclaimer_thread.wait_for_minimum_memory(); >> @@ -842,7 +858,7 @@ static void* malloc_large(size_t size, size_t >> alignment, bool block = true) >> if (alignment > page_size) { >> ret_header = free_page_ranges.alloc_aligned(size, >> page_size, alignment); >> } else { >> - ret_header = free_page_ranges.alloc(size); >> + ret_header = free_page_ranges.alloc(size, contiguous); >> } >> if (ret_header) { >> on_alloc(size); >> @@ -850,6 +866,10 @@ static void* malloc_large(size_t size, size_t >> alignment, bool block = true) >> obj += offset; >> trace_memory_malloc_large(obj, requested_size, size, >> alignment); >> return obj; >> + } else if (!contiguous) { >> + // If we failed to get contiguous memory allocation and >> + // the caller does not require one let us use map-based >> allocation >> + break; >> } >> if (block) >> reclaimer_thread.wait_for_memory(size); >> @@ -857,6 +877,10 @@ static void* malloc_large(size_t size, size_t >> alignment, bool block = true) >> return nullptr; >> } >> } >> + >> + void* obj = mapped_malloc_large(size, offset); >> + trace_memory_malloc_large(obj, requested_size, size, alignment); >> + return obj; >> > > nipick: wouldn't it be clearer to put this code where you have the "break" > above (instead of the "break"), instead of here? > > } >> >> void shrinker::deactivate_shrinker() >> @@ -1072,9 +1096,11 @@ static void free_large(void* obj) >> >> static unsigned large_object_size(void *obj) >> { >> + auto original_obj = obj; >> obj = align_down(obj - 1, page_size); >> > + size_t offset = reinterpret_cast<uint64_t>(original_obj) - >> reinterpret_cast<uint64_t>(obj); >> > auto header = static_cast<page_range*>(obj); >> - return header->size; >> + return header->size - offset; >> > } >> > > I wonder if just this change explains > https://github.com/cloudius-systems/osv/issues/784 and we should close > that issue. > But don't feel an expert enough in this issue to say... > > >> namespace page_pool { >> @@ -1692,7 +1718,7 @@ static inline void* std_malloc(size_t size, size_t >> alignment) >> memory::alloc_page()); >> trace_memory_malloc_page(ret, size, mmu::page_size, alignment); >> } else { >> - ret = memory::malloc_large(size, alignment); >> + ret = memory::malloc_large(size, alignment, true, false); >> } >> memory::tracker_remember(ret, size); >> return ret; >> @@ -1714,6 +1740,14 @@ void* calloc(size_t nmemb, size_t size) >> >> static size_t object_size(void *object) >> { >> + if (!mmu::is_linear_mapped(object, 0)) { >> + auto original_object = object; >> + object = align_down(object - 1, mmu::page_size); >> + size_t offset = reinterpret_cast<uint64_t>(original_object) - >> reinterpret_cast<uint64_t>(object); >> + size_t* ret_header = static_cast<size_t*>(object); >> + return *ret_header - offset; >> > > Can you just call large_object_size() here instead of duplicating its code? > Just like you do below in the mmu::mem_area::main case? > > >> + } >> + >> switch (mmu::get_mem_area(object)) { >> case mmu::mem_area::main: >> return memory::large_object_size(object); >> @@ -1763,6 +1797,14 @@ void free(void* object) >> return; >> } >> memory::tracker_forget(object); >> + >> + if (!mmu::is_linear_mapped(object, 0)) { >> + object = align_down(object - 1, mmu::page_size); >> + size_t* ret_header = static_cast<size_t*>(object); >> + mmu::munmap(object, *ret_header); >> + return; >> > > Nitpick: would be nice to put this code in a function > mapped_free_large(), and put this > function next to mapped_malloc_large() which you already have - so a > reader can see > the two of them next to each other. > > + } >> + >> switch (mmu::get_mem_area(object)) { >> case mmu::mem_area::page: >> object = mmu::translate_mem_area(mmu::mem_area::page, >> @@ -1972,7 +2014,7 @@ void* alloc_phys_contiguous_aligned(size_t size, >> size_t align, bool block) >> assert(is_power_of_two(align)); >> // make use of the standard large allocator returning properly >> aligned >> // physically contiguous memory: >> - auto ret = malloc_large(size, align, block); >> + auto ret = malloc_large(size, align, block, true); >> assert (!(reinterpret_cast<uintptr_t>(ret) & (align - 1))); >> return ret; >> } >> diff --git a/modules/tests/Makefile b/modules/tests/Makefile >> index ce004339..10df022f 100644 >> --- a/modules/tests/Makefile >> +++ b/modules/tests/Makefile >> @@ -129,7 +129,7 @@ tests := tst-pthread.so misc-ramdisk.so tst-vblk.so >> tst-bsd-evh.so \ >> tst-sigaltstack.so tst-fread.so tst-tcp-cork.so tst-tcp-v6.so \ >> tst-calloc.so tst-crypt.so tst-non-fpic.so tst-small-malloc.so \ >> tst-mmx-fpu.so tst-getopt.so tst-getopt-pie.so tst-non-pie.so >> tst-semaphore.so \ >> - tst-elf-init.so >> + tst-elf-init.so tst-realloc.so >> # libstatic-thread-variable.so tst-static-thread-variable.so \ >> >> tests += testrunner.so >> diff --git a/tests/tst-realloc.cc b/tests/tst-realloc.cc >> new file mode 100644 >> index 00000000..49edfb7a >> --- /dev/null >> +++ b/tests/tst-realloc.cc >> @@ -0,0 +1,94 @@ >> +/* >> +* Copyright (C) 2020 Waldemar Kozaczuk >> +* >> +* This work is open source software, licensed under the terms of the >> +* BSD license as described in the LICENSE file in the top-level >> directory. >> +*/ >> + >> +#include <stdlib.h> >> +#include <string.h> >> +#include <cassert> >> +#include <iostream> >> + >> +extern "C" size_t malloc_usable_size (void *ptr); >> + >> +static void test_realloc(size_t original_size, size_t new_size) >> +{ >> + char data[11] = "0123456789"; >> + >> + void *original_buf = malloc(original_size); >> + assert(original_buf); >> + >> + char *buf = static_cast<char*>(original_buf); >> + for (size_t i = 0; i < original_size; i++) { >> + buf[i] = data[i % 10]; >> + } >> + >> + void *new_buf = realloc(original_buf, new_size); >> + assert(new_buf); >> + >> + auto expected_same_data_len = std::min(original_size, new_size); >> + buf = static_cast<char*>(new_buf); >> + for (size_t i = 0; i < expected_same_data_len; i++) { >> + assert(buf[i] == data[i % 10]); >> + } >> + >> + free(new_buf); >> + >> + std::cerr << "PASSED realloc() for original_size: " << original_size >> << ", new_size: " << new_size << std::endl; >> +} >> + >> +static void test_usable_size(size_t size, size_t expected_usable_size) >> +{ >> + void* ptr = malloc(size); >> + assert(expected_usable_size == malloc_usable_size(ptr)); >> + free(ptr); >> + >> + std::cerr << "PASSED malloc_usable_size() for size: " << size << >> std::endl; >> +} >> + >> +int main() >> +{ >> + test_realloc(1,2); >> + test_realloc(2,1); >> + >> + test_realloc(4,7); >> + test_realloc(7,4); >> + >> + test_realloc(63,128); >> + test_realloc(128,63); >> + >> + test_realloc(4000,5000); >> + test_realloc(5000,4000); >> + >> + test_realloc(4096,4096); >> + >> + test_realloc(0x100000,0x100000); >> + test_realloc(0x100000,0x100900); >> + test_realloc(0x100900,0x100000); >> + >> + test_realloc(0x200000,0x200000); >> + test_realloc(0x200000,0x300900); >> + test_realloc(0x300900,0x200000); >> + >> + test_realloc(0x600900,0x600000); >> + test_realloc(0x400000,0x600000); >> + test_realloc(0x600000,0x400900); >> + >> + void *buf = realloc(nullptr, 0); >> + assert(buf); >> + free(buf); >> + >> + buf = malloc(16); >> + assert(!realloc(buf, 0)); >> + >> + test_usable_size(1, 8); >> + test_usable_size(8, 8); >> + test_usable_size(67, 128); >> + test_usable_size(0x4010, 0x4FC0); >> + test_usable_size(0x100000, 0x100FC0); >> + test_usable_size(0x200000, 0x200FC0); >> + >> + std::cerr << "PASSED\n"; >> + return 0; >> +} >> \ No newline at end of file >> -- >> 2.20.1 >> >> -- >> You received this message because you are subscribed to the Google Groups >> "OSv Development" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/osv-dev/20200326183626.12013-1-jwkozaczuk%40gmail.com >> . >> > -- You received this message because you are subscribed to the Google Groups "OSv Development" group. 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