mainlining shenanigans
a562c687d1
These are ilock patches which helps improve the current inode lock scalabiliy problem in ext4 DIO mixed read/write workload case. The problem was first reported by Joseph [1]. This should help improve mixed read/write workload cases for databases which use directIO. These patches are based upon upstream discussion with Jan Kara & Joseph [2]. The problem really is that in case of DIO overwrites, we start with a exclusive lock and then downgrade it later to shared lock. This causes a scalability problem in case of mixed DIO read/write workload case. i.e. if we have any ongoing DIO reads and then comes a DIO writes, (since writes starts with excl. inode lock) then it has to wait until the shared lock is released (which only happens when DIO read is completed). Same is true for vice versa as well. The same can be easily observed with perf-tools trace analysis [3]. For more details, including performance numbers, please see [4]. [1] https://lore.kernel.org/linux-ext4/1566871552-60946-4-git-send-email-joseph.qi@linux.alibaba.com/ [2] https://lore.kernel.org/linux-ext4/20190910215720.GA7561@quack2.suse.cz/ [3] https://raw.githubusercontent.com/riteshharjani/LinuxStudy/master/ext4/perf.report [4] https://lore.kernel.org/r/20191212055557.11151-1-riteshh@linux.ibm.com |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.