88 lines
2.0 KiB
C
88 lines
2.0 KiB
C
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/*
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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 (!buffer_is_zero(page, p->page_size)) {
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memset(page, 0, p->page_size);
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}
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}
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}
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