From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/sysfs-fs-ext4 | 118 ++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-fs-ext4 (limited to 'Documentation/ABI/testing/sysfs-fs-ext4') diff --git a/Documentation/ABI/testing/sysfs-fs-ext4 b/Documentation/ABI/testing/sysfs-fs-ext4 new file mode 100644 index 000000000..2edd0a667 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-fs-ext4 @@ -0,0 +1,118 @@ +What: /sys/fs/ext4//mb_stats +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + Controls whether the multiblock allocator should + collect statistics, which are shown during the unmount. + 1 means to collect statistics, 0 means not to collect + statistics + +What: /sys/fs/ext4//mb_group_prealloc +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + The multiblock allocator will round up allocation + requests to a multiple of this tuning parameter if the + stripe size is not set in the ext4 superblock + +What: /sys/fs/ext4//mb_max_to_scan +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + The maximum number of extents the multiblock allocator + will search to find the best extent + +What: /sys/fs/ext4//mb_min_to_scan +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + The minimum number of extents the multiblock allocator + will search to find the best extent + +What: /sys/fs/ext4//mb_order2_req +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + Tuning parameter which controls the minimum size for + requests (as a power of 2) where the buddy cache is + used + +What: /sys/fs/ext4//mb_stream_req +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + Files which have fewer blocks than this tunable + parameter will have their blocks allocated out of a + block group specific preallocation pool, so that small + files are packed closely together. Each large file + will have its blocks allocated out of its own unique + preallocation pool. + +What: /sys/fs/ext4//inode_readahead_blks +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + Tuning parameter which controls the maximum number of + inode table blocks that ext4's inode table readahead + algorithm will pre-read into the buffer cache + +What: /sys/fs/ext4//delayed_allocation_blocks +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + This file is read-only and shows the number of blocks + that are dirty in the page cache, but which do not + have their location in the filesystem allocated yet. + +What: /sys/fs/ext4//lifetime_write_kbytes +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + This file is read-only and shows the number of kilobytes + of data that have been written to this filesystem since it was + created. + +What: /sys/fs/ext4//session_write_kbytes +Date: March 2008 +Contact: "Theodore Ts'o" +Description: + This file is read-only and shows the number of + kilobytes of data that have been written to this + filesystem since it was mounted. + +What: /sys/fs/ext4//inode_goal +Date: June 2008 +Contact: "Theodore Ts'o" +Description: + Tuning parameter which (if non-zero) controls the goal + inode used by the inode allocator in preference to + all other allocation heuristics. This is intended for + debugging use only, and should be 0 on production + systems. + +What: /sys/fs/ext4//max_writeback_mb_bump +Date: September 2009 +Contact: "Theodore Ts'o" +Description: + The maximum number of megabytes the writeback code will + try to write out before move on to another inode. + +What: /sys/fs/ext4//extent_max_zeroout_kb +Date: August 2012 +Contact: "Theodore Ts'o" +Description: + The maximum number of kilobytes which will be zeroed + out in preference to creating a new uninitialized + extent when manipulating an inode's extent tree. Note + that using a larger value will increase the + variability of time necessary to complete a random + write operation (since a 4k random write might turn + into a much larger write due to the zeroout + operation). + +What: /sys/fs/ext4//journal_task +Date: February 2019 +Contact: "Theodore Ts'o" +Description: + This file is read-only and shows the pid of journal thread in + current pid-namespace or 0 if task is unreachable. -- cgit v1.3.1