e4d2e82b23
This patch adds a path selector that selects paths based on a CPU to path mapping the user passes in and what CPU we are executing on. The primary user for this PS is where the app is optimized to use specific CPUs so other PSs undo the apps handy work, and the storage and it's transport are not a bottlneck. For these io-affinity PS setups a path's transport/interconnect perf is not going to flucuate a lot and there is no major differences between paths, so QL/HST smarts do not help and RR always messes up what the app is trying to do. On a system with 16 cores, where you have a job per CPU: fio --filename=/dev/dm-0 --direct=1 --rw=randrw --bs=4k \ --ioengine=libaio --iodepth=128 --numjobs=16 and a dm-multipath device setup where each CPU is mapped to one path: // When in mq mode I had to set dm_mq_nr_hw_queues=$NUM_PATHS. // Bio mode also showed similar results. 0 16777216 multipath 0 0 1 1 io-affinity 0 16 1 8:16 1 8:32 2 8:64 4 8:48 8 8:80 10 8:96 20 8:112 40 8:128 80 8:144 100 8:160 200 8:176 400 8:192 800 8:208 1000 8:224 2000 8:240 4000 65:0 8000 we can see a IOPs increase of 25%. The percent increase depends on the device and interconnect. For a slower/medium speed path/device that can do around 180K IOPs a path if you ran that fio command to it directly we saw a 25% increase like above. Slower path'd devices that could do around 90K per path showed maybe around a 2 - 5% increase. If you use something like null_blk or scsi_debug which can multi-million IOPs and hack it up so each device they export shows up as a path then you see 50%+ increases. Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> |
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| 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 | ||
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.