If a large file (> 1 GB) is transferred from a USB stick or a mmc to an local disc (using ext4), it will proceed normally until it has transferred approximately 600 MB. Then the speed will drop off to zero and the terminal performing the operation will usually hang. And sometimes other terminals will hang as well. A reboot is required to get the system working again.
mount /dev/sdb1 /mnt pv /mnt/large_file > large_file_out (... ~600 MB ... hang) I have performed a bisect and found that commit ef39794651347 introduced the bug. This commit is present in the latest -next 20150130. From ef397946513470381c0e9ed5b355cd1c9855a364 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o <ty...@mit.edu> Date: Sat, 24 Jan 2015 20:51:05 -0500 Subject: [PATCH] vfs: add support for a lazytime mount option Add a new mount option which enables a new "lazytime" mode. This mode causes atime, mtime, and ctime updates to only be made to the in-memory version of the inode. The on-disk times will only get updated when (a) if the inode needs to be updated for some non-time related change, (b) if userspace calls fsync(), syncfs() or sync(), or (c) just before an undeleted inode is evicted from memory. This is OK according to POSIX because there are no guarantees after a crash unless userspace explicitly requests via a fsync(2) call. For workloads which feature a large number of random write to a preallocated file, the lazytime mount option significantly reduces writes to the inode table. The repeated 4k writes to a single block will result in undesirable stress on flash devices and SMR disk drives. Even on conventional HDD's, the repeated writes to the inode table block will trigger Adjacent Track Interference (ATI) remediation latencies, which very negatively impact long tail latencies --- which is a very big deal for web serving tiers (for example). Google-Bug-Id: 18297052 Signed-off-by: Theodore Ts'o <ty...@mit.edu> --- fs/ext4/inode.c | 6 ++++ fs/fs-writeback.c | 62 +++++++++++++++++++++++++++++++++------- fs/gfs2/file.c | 4 +-- fs/inode.c | 56 +++++++++++++++++++++++++----------- fs/jfs/file.c | 2 +- fs/libfs.c | 2 +- fs/proc_namespace.c | 1 + fs/sync.c | 8 ++++++ include/linux/backing-dev.h | 1 + include/linux/fs.h | 5 ++++ include/trace/events/writeback.h | 60 +++++++++++++++++++++++++++++++++++++- include/uapi/linux/fs.h | 4 ++- mm/backing-dev.c | 10 +++++-- 13 files changed, 186 insertions(+), 35 deletions(-) If I can do anything else to help, let me know. -- - Jeremiah Mahler -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
