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Linux Multi-Queue Block IO Queueing Mechanism (blk-mq) Details - Thomas-Krenn-Wiki-en
Blk-mq integrates seamlessly into the Linux storage stack. It provides basic functions to device drivers for mapping I/O enquiries to multiple queues. The tasks are distributed across multiple threads and therefore to multiple CPU cores (per-core software queues). Blk-mq compatible drivers inform blk-mq how many parallel hardware queues a device supports (number of submission queues as part of the
Linuxカーãƒãƒ«5.0ã§ã¯CFQ, Deadlineã¨è¨€ã£ãŸã‚·ãƒ³ã‚°ãƒ«ã‚ュースケジューラãŒå…¨ã¦å‰Šé™¤ã•ã‚Œã¦ã‚«ãƒ¼ãƒãƒ«ã®ãƒ‡ãƒ•ã‚©ãƒ«ãƒˆIOスケジューラè¨å®šã‚‚ç„¡ããªã£ã¦ã„ã¾ã—ãŸ
Linuxカーãƒãƒ«5.0ã§ã¯CFQ, Deadlineã¨è¨€ã£ãŸã‚·ãƒ³ã‚°ãƒ«ã‚ュースケジューラãŒå…¨ã¦å‰Šé™¤ã•ã‚Œã¦ã‚«ãƒ¼ãƒãƒ«ã®ãƒ‡ãƒ•ã‚©ãƒ«ãƒˆIOスケジューラè¨å®šã‚‚ç„¡ããªã£ã¦ã„ã¾ã—㟠Linux 5.0ã§ã®å¤‰æ›´ 5.0ã§ã®å…¨ä½“ã®å¤‰æ›´ã¯ã“ã“ã§è¦‹ã‚Œã¾ã™. 今回ビックリã—ãŸã®ã¯ block/cfq-iosched.c 㨠block/deadline-iosched.c ã®å‰Šé™¤ã§ã™. CFQãŒä¸»ã«SSDã§æ€§èƒ½ãŒè‰¯ããªã„ã“ã¨ã¯çŸ¥ã£ã¦ã„ã¾ã—ãŸãŒ, DeadlineãŒå‰Šé™¤ã•ã‚Œã‚‹ã¨ã¯æ€ã£ã¦ã„ã¾ã›ã‚“ã§ã—ãŸ. ã¾ã‚パフォーマンスã®æœ€å¤§åŒ– - ArchWiki ã‚’ä¿¡ã˜ã‚‹ãªã‚‰CFQã¨Deadlineã¯ãƒžãƒ«ãƒã‚¹ãƒ¬ãƒƒãƒ‰ã«å¯¾å¿œã—ã¦ã„ãªã„ã®ã§å‰Šé™¤ã¯æ™‚代ã®æµã‚Œã§ã—ょã†. 言åŠã¯ã‚³ãƒŸãƒƒãƒˆä¸Šã§ã¯ã“ã“ã§ã•ã‚Œã¦ã„ã¾ã™. ã™ã”ã„ç ´å£Šçš„å¤‰æ›´ãªã®ã«, Linux 5.0ã®ãƒªãƒªãƒ¼ã‚¹ãƒ‹ãƒ¥ãƒ¼ã‚¹ã«ã‚‚ãƒã‚§ãƒ³ã‚¸ãƒã‚°ã‚’ã¾ã¨ã‚ãŸã‚µã‚¤ãƒˆã§ã‚‚全然å–り上ã’られã¦ç„¡ãã¦, m
btrfs? Dropboxã•ã‚“, ã‚ãªãŸãŒè¦‹ã¦ã„ã‚‹ã®ã¯ext4ã§ã™ã‚ˆ - Gentoo metalog
注æ„: ã“ã®è¨˜äº‹ã®å†…容ã¯ã‚ã‚Šã¨å±é™ºãªéƒ¨åˆ†ãŒã‚ã‚Šã¾ã™. 使ã„ãŸããªã£ã¦ã‚‚よã注æ„ã—ã¦ç†è§£ã—ã¦ä½¿ã£ã¦ãã ã•ã„ ã‚ãŸã—ã‚‚ã¾ã 大ã—ã¦å®Ÿå‹•ãƒ†ã‚¹ãƒˆã—ã¦ã¾ã›ã‚“. Dropboxã®ä¸èº«ãŒæ¶ˆå¤±ã—ãŸã‚Š, FSãŒã“ã‚ã‚ŒãŸã‚Š, ãªã‚“ã‹ãŠã‚‚ã—ã‚ã„ã“ã¨ã«ãªã£ã¦ã‚‚責任ã¯ä¸€åˆ‡ã¨ã‚Œã¾ã›ã‚“. 技術的ãªè¦³è³žç”¨ã«ç•™ã‚ã‚‹ã®ãŒç„¡é›£ã§ã™ ã¯ã˜ã‚ã« DropboxãŒext4ã—ã‹å¯¾å¿œã—ãªããªã‚‹ã‚‰ã—ã„ã§ã™ã. btrfs愛用者ã¨ã—ã¦ã¯ãƒãƒãƒ£ãƒ¡ãƒãƒ£ã‚ã‚“ã©ã„ã§ã™. ã¨ã„ã†ã“ã¨ã§, ãªã‚“ã¨ã‹ã—ãŸããªã‚Šã¾ã™ã. 1ã¤ã®æ–¹æ³•ã¨ã—ã¦, 下ã®è¨˜äº‹ã®ã‚ˆã†ã«btrfs上ã«ext4ã®ã‚¤ãƒ¡ãƒ¼ã‚¸ãƒ•ã‚¡ã‚¤ãƒ«ã‚’作ã£ã¦ã‚ã’ã‚‹ã¨ã„ã†æ–¹æ³•ãŒã‚ã‚Šã¾ã™. qiita.com ãŸã ã“ã®æ–¹æ³•ã ã¨, kernelã®ä¸ã§ç„¡é§„ã«ext4ã‚’Dropboxã®ãŸã‚ã ã‘ã«å‹•ã‹ã™ã“ã¨ã«ãªã‚Šã¾ã™ã. ext4ã®moduleãªã‚“ã‹ç½®ã„ã¦ãŠããŸããªã„. ãã†æ€ã„ã¾ã›ã‚“㋠システムコールã®çµæžœã‚’書ãã‹ãˆã‚‹
ext4ã®noauto_da_allocオプションã®è©³ç´° - Qiita
ã¾ãšã¯çµè«– Linux-3.18ãらã„を見ã¦æ›¸ã„ã¦ã¾ã™ã€‚ よãã‚ã‹ã‚‰ãªã„å ´åˆ ã‚ªãƒ—ã‚·ãƒ§ãƒ³ã¯ä½•ã‚‚足ã™ãªã€‚何も削るãªã€‚ ã‚ã‹ã£ãŸä¸Šã§ãƒ‘フォーマンス上ã’ãŸã„å ´åˆ noauto_da_alloc を足ã™ã€‚ アプリã®å®Ÿè£…ミスã§ã‚ã‚ã†ãŒãªã‹ã‚ã†ãŒã€é›»æºæ–ã§ãƒ•ã‚¡ã‚¤ãƒ«ãŒæ¶ˆãˆã‚‹ã®ãŒæ€–ãã¦å¤œã‚‚å¯ã‚‰ã‚Œãªã„å ´åˆ journal_checksum data=journal ãらã„？ (data=journalã«ã™ã‚‹ã¨è‡ªå‹•ã§nodelallocも有効ã«ãªã‚‹) (nodelallocã ã¨noauto_da_allocã¯æ„味をãªã•ãªã„) é›»æºæ–？ãã‚“ãªã®ã„ã„ã‹ã‚‰æœ€é€Ÿã‚’目指ã™ãœ noauto_da_alloc nobarrier journal_async_commit noatime data=writeback ãらã„？ ・・・tune2fs(8)使ã£ã¦journalãªã—ã«ã™ã‚‹ï¼Ÿã‚€ã—ã‚ext4ãªã‚“ã¦ã‚„ã‚ãŸæ–¹ãŒãƒ»ãƒ»ãƒ» ã¯
Linux_2_6_32 - Linux Kernel Newbies
Linux 2.6.32 has been released on December 3rd 2009. Summary: This version adds virtualization memory de-duplication, a rewrite of the writeback code which provides noticeable performance speedups, many important Btrfs improvements and speedups, ATI R600/R700 3D and KMS support and other graphic improvements, a CFQ low latency mode, tracing improvements including a "perf timechart" tool that tries
Flushing out pdflush [LWN.net]
April 1, 2009 This article was contributed by Goldwyn Rodrigues The kernel page cache contains in-memory copies of data blocks belonging to files kept in persistent storage. Pages which are written to by a processor, but not yet written to disk, are accumulated in cache and are known as "dirty" pages. The amount of dirty memory is listed in /proc/meminfo. Pages in the cache are flushed to disk aft
How sync_file_range() really works
There is a relatively new and platform dependent flushing function called sync_file_range(). Some databases (not MySQL) use sync_file_range() internally. Recently I investigated stall issues caused by buffered write and sync_file_range(). I learned a lot during investigation but I don't think these behaviors are well known to the public. Here I summarize my understandings. Understanding difference
Linux I/O scheduler queue size and MyISAM performance
At MySQL Conference and Expo 2009, I explained how Linux I/O scheduler queue size affects MyISAM insert performance. It is well known that Linux implemented four types of I/O schedulers (noop/deadline/anticipatory/cfq) in Linux kernel 2.6.10. The default is cfq in most distributions including RHEL, which is not so good then noop normally outperforms, but I'll talk this in other posts. Linux I/O sc
Tracing and Profiling - Yocto Project
Tracing and Profiling in Yocto Yocto bundles a number of tracing and profiling tools - this 'HOWTO' describes their basic usage and shows by example how to make use of them to examine application and system behavior. The tools presented are for the most part completely open-ended and have quite good and/or extensive documentation of their own which can be used to solve just about any problem you m
Ensuring data reaches disk [LWN.net]
Please consider subscribing to LWNSubscriptions are the lifeblood of LWN.net. If you appreciate this content and would like to see more of it, your subscription will help to ensure that LWN continues to thrive. Please visit this page to join up and keep LWN on the net. In a perfect world, there would be no operating system crashes, power outages or disk failures, and programmers wouldn't have to w
![Ensuring data reaches disk [LWN.net]](https://cdn-ak-scissors.b.st-hatena.com/image/square/6b330395eb6a3a4002d6aa19c1d6d71ad3930378/height=288;version=1;width=512/https%3A%2F%2Fstatic.lwn.net%2Fimages%2F2011%2Fjm-data-flow.png)
Efficient File Copying On Linux
In response to my last post about dd, a friend of mine noticed that GNU cp always uses a 128 KB buffer size when copying a regular file; this is also the buffer size used by GNU cat. If you use strace to watch what happens when copying a file, you should see a lot of 128 KB read/write sequences: $ strace -s 8 -xx cp /dev/urandom /dev/null ... read(3, "\x61\xca\xf8\xff\x1a\xd6\x83\x8b"..., 131072)
Which I/O controller is the fairest of them all? [LWN.net]
An I/O controller is a system component intended to arbitrate access to block storage devices; it should ensure that different groups of processes get specific levels of access according to a policy defined by the system administrator. In other words, it prevents I/O-intensive processes from hogging the disk. This feature can be useful on just about any kind of system which experiences disk conten
Block layer introduction part 2: the request layer [LWN.net]
November 9, 2017 This article was contributed by Neil Brown The Linux block layer provides an upstream interface to filesystems and block-special devices allowing them to access a multitude of storage backends in a uniform manner. It also provides downstream interfaces to device drivers and driver-support frameworks that allow those drivers and frameworks to receive requests in a manner most suita
A block layer introduction part 1: the bio layer [LWN.net]
October 25, 2017 This article was contributed by Neil Brown One of the key values provided by an operating system like Linux is that it provides abstract interfaces to concrete devices. Though the original "character device" and "block device" abstractions have been supplemented with various others including "network device" and "bitmap display", the original two have not lost their importance. Th
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Using an external journal with ext4 – Jean's Blog
ext4: using external journal to optimise performance
Dynamic writeback throttling [LWN.net]
https://www.kernel.org/doc/Documentation/trace/ftrace.txt
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