From: Phillip Susi <phill@thesusis.net>
To: Jan Ziak <0xe2.0x9a.0x9b@gmail.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Btrfs autodefrag wrote 5TB in one day to a 0.5TB SSD without a measurable benefit
Date: Mon, 14 Mar 2022 16:02:41 -0400 [thread overview]
Message-ID: <87ee34cnaq.fsf@vps.thesusis.net> (raw)
In-Reply-To: <CAODFU0oM02WDpOPXp1of177aEJ9=ux2QFrHZF=khhzAg+3N1dA@mail.gmail.com>
Jan Ziak <0xe2.0x9a.0x9b@gmail.com> writes:
> The actual disk usage of a file in a copy-on-write filesystem can be
> much larger than sb.st_size obtained via fstat(fd, &sb) if, for
> example, a program performs many (millions) single-byte file changes
> using write(fd, buf, 1) to distinct/random offsets in the file.
How? I mean if you write to part of the file a new block is written
somewhere else but the original one is then freed, so the overall size
should not change. Just because all of the blocks of the file are not
contiguous does not mean that the file has more of them, and making them
contiguous does not reduce the number of them.
next prev parent reply other threads:[~2022-03-14 20:06 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-06 15:59 Btrfs autodefrag wrote 5TB in one day to a 0.5TB SSD without a measurable benefit Jan Ziak
2022-03-07 0:48 ` Qu Wenruo
2022-03-07 2:23 ` Jan Ziak
2022-03-07 2:39 ` Qu Wenruo
2022-03-07 7:31 ` Qu Wenruo
2022-03-10 1:10 ` Jan Ziak
2022-03-10 1:26 ` Qu Wenruo
2022-03-10 4:33 ` Jan Ziak
2022-03-10 6:42 ` Qu Wenruo
2022-03-10 21:31 ` Jan Ziak
2022-03-10 23:27 ` Qu Wenruo
2022-03-11 2:42 ` Jan Ziak
2022-03-11 2:59 ` Qu Wenruo
2022-03-11 5:04 ` Jan Ziak
2022-03-11 16:31 ` Jan Ziak
2022-03-11 20:02 ` Jan Ziak
2022-03-11 23:04 ` Qu Wenruo
2022-03-11 23:28 ` Jan Ziak
2022-03-11 23:39 ` Qu Wenruo
2022-03-12 0:01 ` Jan Ziak
2022-03-12 0:15 ` Qu Wenruo
2022-03-12 3:16 ` Zygo Blaxell
2022-03-12 2:43 ` Zygo Blaxell
2022-03-12 3:24 ` Qu Wenruo
2022-03-12 3:48 ` Zygo Blaxell
2022-03-14 20:09 ` Phillip Susi
2022-03-14 22:59 ` Zygo Blaxell
2022-03-15 18:28 ` Phillip Susi
2022-03-15 19:28 ` Jan Ziak
2022-03-15 21:06 ` Zygo Blaxell
2022-03-15 22:20 ` Jan Ziak
2022-03-16 17:02 ` Zygo Blaxell
2022-03-16 17:48 ` Jan Ziak
2022-03-17 2:11 ` Zygo Blaxell
2022-03-16 18:46 ` Phillip Susi
2022-03-16 19:59 ` Zygo Blaxell
2022-03-20 17:50 ` Forza
2022-03-20 21:15 ` Zygo Blaxell
2022-03-08 21:57 ` Jan Ziak
2022-03-08 23:40 ` Qu Wenruo
2022-03-09 22:22 ` Jan Ziak
2022-03-09 22:44 ` Qu Wenruo
2022-03-09 22:55 ` Jan Ziak
2022-03-09 23:00 ` Jan Ziak
2022-03-09 4:48 ` Zygo Blaxell
2022-03-07 14:30 ` Phillip Susi
2022-03-08 21:43 ` Jan Ziak
2022-03-09 18:46 ` Phillip Susi
2022-03-09 21:35 ` Jan Ziak
2022-03-14 20:02 ` Phillip Susi [this message]
2022-03-14 21:53 ` Jan Ziak
2022-03-14 22:24 ` Remi Gauvin
2022-03-14 22:51 ` Zygo Blaxell
2022-03-14 23:07 ` Remi Gauvin
2022-03-14 23:39 ` Zygo Blaxell
2022-03-15 14:14 ` Remi Gauvin
2022-03-15 18:51 ` Zygo Blaxell
2022-03-15 19:22 ` Remi Gauvin
2022-03-15 21:08 ` Zygo Blaxell
2022-03-15 18:15 ` Phillip Susi
2022-03-16 16:52 ` Andrei Borzenkov
2022-03-16 18:28 ` Jan Ziak
2022-03-16 18:31 ` Phillip Susi
2022-03-16 18:43 ` Andrei Borzenkov
2022-03-16 18:46 ` Jan Ziak
2022-03-16 19:04 ` Zygo Blaxell
2022-03-17 20:34 ` Phillip Susi
2022-03-17 22:06 ` Zygo Blaxell
2022-03-16 12:47 ` Kai Krakow
2022-03-16 18:18 ` Jan Ziak
2022-06-17 0:20 Jan Ziak
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