5ef7e26bdb
Implemented recvbitmap tracking of received pages in multifd. If the zero page appears for the first time in the recvbitmap, this page is not checked and set. If the zero page has already appeared in the recvbitmap, there is no need to check the data but directly set the data to 0, because it is unlikely that the zero page will be migrated multiple times. Signed-off-by: Yuan Liu <yuan1.liu@intel.com> Reviewed-by: Fabiano Rosas <farosas@suse.de> Link: https://lore.kernel.org/r/20240401154110.2028453-2-yuan1.liu@intel.com [peterx: touch up the comment, as the bitmap is used outside postcopy now] Signed-off-by: Peter Xu <peterx@redhat.com>
90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
/*
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* Multifd zero page detection implementation.
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*
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* Copyright (c) 2024 Bytedance Inc
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*
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* Authors:
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* Hao Xiang <hao.xiang@bytedance.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "exec/ramblock.h"
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#include "migration.h"
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#include "multifd.h"
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#include "options.h"
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#include "ram.h"
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static bool multifd_zero_page_enabled(void)
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{
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return migrate_zero_page_detection() == ZERO_PAGE_DETECTION_MULTIFD;
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}
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static void swap_page_offset(ram_addr_t *pages_offset, int a, int b)
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{
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ram_addr_t temp;
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if (a == b) {
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return;
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}
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temp = pages_offset[a];
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pages_offset[a] = pages_offset[b];
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pages_offset[b] = temp;
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}
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/**
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* multifd_send_zero_page_detect: Perform zero page detection on all pages.
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*
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* Sorts normal pages before zero pages in p->pages->offset and updates
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* p->pages->normal_num.
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*
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* @param p A pointer to the send params.
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*/
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void multifd_send_zero_page_detect(MultiFDSendParams *p)
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{
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MultiFDPages_t *pages = p->pages;
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RAMBlock *rb = pages->block;
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int i = 0;
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int j = pages->num - 1;
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if (!multifd_zero_page_enabled()) {
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pages->normal_num = pages->num;
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return;
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}
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/*
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* Sort the page offset array by moving all normal pages to
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* the left and all zero pages to the right of the array.
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*/
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while (i <= j) {
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uint64_t offset = pages->offset[i];
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if (!buffer_is_zero(rb->host + offset, p->page_size)) {
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i++;
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continue;
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}
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swap_page_offset(pages->offset, i, j);
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ram_release_page(rb->idstr, offset);
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j--;
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}
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pages->normal_num = i;
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}
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void multifd_recv_zero_page_process(MultiFDRecvParams *p)
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{
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for (int i = 0; i < p->zero_num; i++) {
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void *page = p->host + p->zero[i];
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if (ramblock_recv_bitmap_test_byte_offset(p->block, p->zero[i])) {
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memset(page, 0, p->page_size);
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} else {
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ramblock_recv_bitmap_set_offset(p->block, p->zero[i]);
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}
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}
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}
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