130 lines
4.7 KiB
Diff
130 lines
4.7 KiB
Diff
From 9ca4e437a24dfc4ec6c362f319eb9850b9eca497 Mon Sep 17 00:00:00 2001
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From: Yu Zhao <yuzhao@google.com>
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Date: Fri, 30 Dec 2022 14:52:52 -0700
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Subject: [PATCH 11/19] UPSTREAM: mm: support POSIX_FADV_NOREUSE
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This patch adds POSIX_FADV_NOREUSE to vma_has_recency() so that the LRU
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algorithm can ignore access to mapped files marked by this flag.
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The advantages of POSIX_FADV_NOREUSE are:
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1. Unlike MADV_SEQUENTIAL and MADV_RANDOM, it does not alter the
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default readahead behavior.
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2. Unlike MADV_SEQUENTIAL and MADV_RANDOM, it does not split VMAs and
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therefore does not take mmap_lock.
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3. Unlike MADV_COLD, setting it has a negligible cost, regardless of
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how many pages it affects.
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Its limitations are:
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1. Like POSIX_FADV_RANDOM and POSIX_FADV_SEQUENTIAL, it currently does
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not support range. IOW, its scope is the entire file.
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2. It currently does not ignore access through file descriptors.
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Specifically, for the active/inactive LRU, given a file page shared
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by two users and one of them having set POSIX_FADV_NOREUSE on the
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file, this page will be activated upon the second user accessing
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it. This corner case can be covered by checking POSIX_FADV_NOREUSE
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before calling folio_mark_accessed() on the read path. But it is
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considered not worth the effort.
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There have been a few attempts to support POSIX_FADV_NOREUSE, e.g., [1].
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This time the goal is to fill a niche: a few desktop applications, e.g.,
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large file transferring and video encoding/decoding, want fast file
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streaming with mmap() rather than direct IO. Among those applications, an
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SVT-AV1 regression was reported when running with MGLRU [2]. The
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following test can reproduce that regression.
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kb=$(awk '/MemTotal/ { print $2 }' /proc/meminfo)
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kb=$((kb - 8*1024*1024))
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modprobe brd rd_nr=1 rd_size=$kb
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dd if=/dev/zero of=/dev/ram0 bs=1M
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mkfs.ext4 /dev/ram0
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mount /dev/ram0 /mnt/
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swapoff -a
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fallocate -l 8G /mnt/swapfile
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mkswap /mnt/swapfile
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swapon /mnt/swapfile
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wget http://ultravideo.cs.tut.fi/video/Bosphorus_3840x2160_120fps_420_8bit_YUV_Y4M.7z
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7z e -o/mnt/ Bosphorus_3840x2160_120fps_420_8bit_YUV_Y4M.7z
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SvtAv1EncApp --preset 12 -w 3840 -h 2160 \
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-i /mnt/Bosphorus_3840x2160.y4m
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For MGLRU, the following change showed a [9-11]% increase in FPS,
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which makes it on par with the active/inactive LRU.
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patch Source/App/EncApp/EbAppMain.c <<EOF
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31a32
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> #include <fcntl.h>
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35d35
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< #include <fcntl.h> /* _O_BINARY */
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117a118
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> posix_fadvise(config->mmap.fd, 0, 0, POSIX_FADV_NOREUSE);
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EOF
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[1] https://lore.kernel.org/r/1308923350-7932-1-git-send-email-andrea@betterlinux.com/
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[2] https://openbenchmarking.org/result/2209259-PTS-MGLRU8GB57
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Link: https://lkml.kernel.org/r/20221230215252.2628425-2-yuzhao@google.com
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Change-Id: I0b7f5f971d78014ea1ba44cee6a8ec902a4330d0
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Signed-off-by: Yu Zhao <yuzhao@google.com>
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Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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Cc: Andrea Righi <andrea.righi@canonical.com>
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Cc: Johannes Weiner <hannes@cmpxchg.org>
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Cc: Michael Larabel <Michael@MichaelLarabel.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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(cherry picked from commit 17e810229cb3068b692fa078bd9b3a6527e0866a)
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Bug: 274865848
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Signed-off-by: T.J. Mercier <tjmercier@google.com>
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---
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include/linux/fs.h | 2 ++
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include/linux/mm_inline.h | 3 +++
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mm/fadvise.c | 5 ++++-
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3 files changed, 9 insertions(+), 1 deletion(-)
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--- a/include/linux/fs.h
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+++ b/include/linux/fs.h
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@@ -166,6 +166,8 @@ typedef int (dio_iodone_t)(struct kiocb
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/* File supports DIRECT IO */
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#define FMODE_CAN_ODIRECT ((__force fmode_t)0x400000)
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+#define FMODE_NOREUSE ((__force fmode_t)0x800000)
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+
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/* File was opened by fanotify and shouldn't generate fanotify events */
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#define FMODE_NONOTIFY ((__force fmode_t)0x4000000)
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--- a/include/linux/mm_inline.h
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+++ b/include/linux/mm_inline.h
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@@ -605,6 +605,9 @@ static inline bool vma_has_recency(struc
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if (vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ))
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return false;
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+ if (vma->vm_file && (vma->vm_file->f_mode & FMODE_NOREUSE))
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+ return false;
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+
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return true;
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}
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--- a/mm/fadvise.c
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+++ b/mm/fadvise.c
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@@ -80,7 +80,7 @@ int generic_fadvise(struct file *file, l
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case POSIX_FADV_NORMAL:
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file->f_ra.ra_pages = bdi->ra_pages;
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spin_lock(&file->f_lock);
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- file->f_mode &= ~FMODE_RANDOM;
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+ file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE);
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spin_unlock(&file->f_lock);
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break;
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case POSIX_FADV_RANDOM:
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@@ -107,6 +107,9 @@ int generic_fadvise(struct file *file, l
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force_page_cache_readahead(mapping, file, start_index, nrpages);
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break;
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case POSIX_FADV_NOREUSE:
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+ spin_lock(&file->f_lock);
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+ file->f_mode |= FMODE_NOREUSE;
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+ spin_unlock(&file->f_lock);
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break;
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case POSIX_FADV_DONTNEED:
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__filemap_fdatawrite_range(mapping, offset, endbyte,
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