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![Alex Sierra](/assets/img/avatar_default.png)
Patch series "Add MEMORY_DEVICE_COHERENT for coherent device memory mapping", v9. This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory owned by a device that can be mapped into CPU page tables like MEMORY_DEVICE_GENERIC and can also be migrated like MEMORY_DEVICE_PRIVATE. This patch series is mostly self-contained except for a few places where it needs to update other subsystems to handle the new memory type. System stability and performance are not affected according to our ongoing testing, including xfstests. How it works: The system BIOS advertises the GPU device memory (aka VRAM) as SPM (special purpose memory) in the UEFI system address map. The amdgpu driver registers the memory with devmap as MEMORY_DEVICE_COHERENT using devm_memremap_pages. The initial user for this hardware page migration capability is the Frontier supercomputer project. This functionality is not AMD-specific. We expect other GPU vendors to find this functionality useful, and possibly other hardware types in the future. Our test nodes in the lab are similar to the Frontier configuration, with .5 TB of system memory plus 256 GB of device memory split across 4 GPUs, all in a single coherent address space. Page migration is expected to improve application efficiency significantly. We will report empirical results as they become available. Coherent device type pages at gup are now migrated back to system memory if they are being pinned long-term (FOLL_LONGTERM). The reason is, that long-term pinning would interfere with the device memory manager owning the device-coherent pages (e.g. evictions in TTM). These series incorporate Alistair Popple patches to do this migration from pin_user_pages() calls. hmm_gup_test has been added to hmm-test to test different get user pages calls. This series includes handling of device-managed anonymous pages returned by vm_normal_pages. Although they behave like normal pages for purposes of mapping in CPU page tables and for COW, they do not support LRU lists, NUMA migration or THP. We also introduced a FOLL_LRU flag that adds the same behaviour to follow_page and related APIs, to allow callers to specify that they expect to put pages on an LRU list. This patch (of 14): is_pinnable_page() and folio_is_pinnable() are renamed to is_longterm_pinnable_page() and folio_is_longterm_pinnable() respectively. These functions are used in the FOLL_LONGTERM flag context. Link: https://lkml.kernel.org/r/20220715150521.18165-1-alex.sierra@amd.com Link: https://lkml.kernel.org/r/20220715150521.18165-2-alex.sierra@amd.com Signed-off-by: Alex Sierra <alex.sierra@amd.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
250 lines
5.6 KiB
C
250 lines
5.6 KiB
C
#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/ktime.h>
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#include <linux/debugfs.h>
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#include "gup_test.h"
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static void put_back_pages(unsigned int cmd, struct page **pages,
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unsigned long nr_pages, unsigned int gup_test_flags)
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{
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unsigned long i;
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switch (cmd) {
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case GUP_FAST_BENCHMARK:
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case GUP_BASIC_TEST:
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for (i = 0; i < nr_pages; i++)
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put_page(pages[i]);
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break;
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case PIN_FAST_BENCHMARK:
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case PIN_BASIC_TEST:
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case PIN_LONGTERM_BENCHMARK:
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unpin_user_pages(pages, nr_pages);
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break;
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case DUMP_USER_PAGES_TEST:
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if (gup_test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN) {
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unpin_user_pages(pages, nr_pages);
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} else {
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for (i = 0; i < nr_pages; i++)
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put_page(pages[i]);
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}
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break;
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}
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}
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static void verify_dma_pinned(unsigned int cmd, struct page **pages,
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unsigned long nr_pages)
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{
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unsigned long i;
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struct page *page;
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switch (cmd) {
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case PIN_FAST_BENCHMARK:
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case PIN_BASIC_TEST:
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case PIN_LONGTERM_BENCHMARK:
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for (i = 0; i < nr_pages; i++) {
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page = pages[i];
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if (WARN(!page_maybe_dma_pinned(page),
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"pages[%lu] is NOT dma-pinned\n", i)) {
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dump_page(page, "gup_test failure");
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break;
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} else if (cmd == PIN_LONGTERM_BENCHMARK &&
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WARN(!is_longterm_pinnable_page(page),
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"pages[%lu] is NOT pinnable but pinned\n",
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i)) {
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dump_page(page, "gup_test failure");
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break;
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}
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}
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break;
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}
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}
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static void dump_pages_test(struct gup_test *gup, struct page **pages,
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unsigned long nr_pages)
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{
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unsigned int index_to_dump;
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unsigned int i;
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/*
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* Zero out any user-supplied page index that is out of range. Remember:
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* .which_pages[] contains a 1-based set of page indices.
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*/
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for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
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if (gup->which_pages[i] > nr_pages) {
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pr_warn("ZEROING due to out of range: .which_pages[%u]: %u\n",
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i, gup->which_pages[i]);
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gup->which_pages[i] = 0;
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}
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}
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for (i = 0; i < GUP_TEST_MAX_PAGES_TO_DUMP; i++) {
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index_to_dump = gup->which_pages[i];
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if (index_to_dump) {
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index_to_dump--; // Decode from 1-based, to 0-based
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pr_info("---- page #%u, starting from user virt addr: 0x%llx\n",
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index_to_dump, gup->addr);
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dump_page(pages[index_to_dump],
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"gup_test: dump_pages() test");
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}
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}
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}
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static int __gup_test_ioctl(unsigned int cmd,
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struct gup_test *gup)
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{
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ktime_t start_time, end_time;
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unsigned long i, nr_pages, addr, next;
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long nr;
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struct page **pages;
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int ret = 0;
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bool needs_mmap_lock =
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cmd != GUP_FAST_BENCHMARK && cmd != PIN_FAST_BENCHMARK;
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if (gup->size > ULONG_MAX)
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return -EINVAL;
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nr_pages = gup->size / PAGE_SIZE;
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pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);
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if (!pages)
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return -ENOMEM;
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if (needs_mmap_lock && mmap_read_lock_killable(current->mm)) {
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ret = -EINTR;
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goto free_pages;
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}
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i = 0;
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nr = gup->nr_pages_per_call;
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start_time = ktime_get();
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for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
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if (nr != gup->nr_pages_per_call)
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break;
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next = addr + nr * PAGE_SIZE;
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if (next > gup->addr + gup->size) {
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next = gup->addr + gup->size;
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nr = (next - addr) / PAGE_SIZE;
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}
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switch (cmd) {
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case GUP_FAST_BENCHMARK:
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nr = get_user_pages_fast(addr, nr, gup->gup_flags,
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pages + i);
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break;
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case GUP_BASIC_TEST:
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nr = get_user_pages(addr, nr, gup->gup_flags, pages + i,
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NULL);
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break;
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case PIN_FAST_BENCHMARK:
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nr = pin_user_pages_fast(addr, nr, gup->gup_flags,
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pages + i);
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break;
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case PIN_BASIC_TEST:
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nr = pin_user_pages(addr, nr, gup->gup_flags, pages + i,
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NULL);
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break;
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case PIN_LONGTERM_BENCHMARK:
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nr = pin_user_pages(addr, nr,
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gup->gup_flags | FOLL_LONGTERM,
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pages + i, NULL);
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break;
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case DUMP_USER_PAGES_TEST:
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if (gup->test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
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nr = pin_user_pages(addr, nr, gup->gup_flags,
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pages + i, NULL);
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else
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nr = get_user_pages(addr, nr, gup->gup_flags,
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pages + i, NULL);
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break;
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default:
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ret = -EINVAL;
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goto unlock;
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}
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if (nr <= 0)
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break;
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i += nr;
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}
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end_time = ktime_get();
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/* Shifting the meaning of nr_pages: now it is actual number pinned: */
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nr_pages = i;
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gup->get_delta_usec = ktime_us_delta(end_time, start_time);
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gup->size = addr - gup->addr;
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/*
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* Take an un-benchmark-timed moment to verify DMA pinned
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* state: print a warning if any non-dma-pinned pages are found:
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*/
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verify_dma_pinned(cmd, pages, nr_pages);
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if (cmd == DUMP_USER_PAGES_TEST)
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dump_pages_test(gup, pages, nr_pages);
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start_time = ktime_get();
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put_back_pages(cmd, pages, nr_pages, gup->test_flags);
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end_time = ktime_get();
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gup->put_delta_usec = ktime_us_delta(end_time, start_time);
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unlock:
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if (needs_mmap_lock)
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mmap_read_unlock(current->mm);
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free_pages:
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kvfree(pages);
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return ret;
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}
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static long gup_test_ioctl(struct file *filep, unsigned int cmd,
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unsigned long arg)
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{
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struct gup_test gup;
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int ret;
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switch (cmd) {
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case GUP_FAST_BENCHMARK:
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case PIN_FAST_BENCHMARK:
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case PIN_LONGTERM_BENCHMARK:
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case GUP_BASIC_TEST:
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case PIN_BASIC_TEST:
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case DUMP_USER_PAGES_TEST:
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break;
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default:
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return -EINVAL;
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}
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if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
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return -EFAULT;
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ret = __gup_test_ioctl(cmd, &gup);
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if (ret)
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return ret;
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if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
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return -EFAULT;
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return 0;
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}
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static const struct file_operations gup_test_fops = {
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.open = nonseekable_open,
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.unlocked_ioctl = gup_test_ioctl,
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};
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static int __init gup_test_init(void)
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{
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debugfs_create_file_unsafe("gup_test", 0600, NULL, NULL,
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&gup_test_fops);
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return 0;
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}
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late_initcall(gup_test_init);
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