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A mirror of the official Linux kernel repository just in case
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With memory backing disabled, using a single spinlock for protecting zone information and zone resource management prevents the parallel execution on multiple queue of IO requests to different zones. Furthermore, regardless of the use of memory backing, if a null_blk device is created without limits on the number of open and active zones, accounting for zone resource management is not necessary. >From these observations, zone locking is changed as follows to improve performance: 1) the zone_lock spinlock is renamed zone_res_lock and used only if zone resource management is necessary, that is, if either zone_max_open or zone_max_active are not 0. This is indicated using the new boolean need_zone_res_mgmt in the nullb_device structure. null_zone_write() is modified to reduce the amount of code executed with the zone_res_lock spinlock held. 2) With memory backing disabled, per zone locking is changed to a spinlock per zone. 3) Introduce the structure nullb_zone to replace the use of struct blk_zone for zone information. This new structure includes a union of a spinlock and a mutex for zone locking. The spinlock is used when memory backing is disabled and the mutex is used with memory backing. With these changes, fio performance with zonemode=zbd for 4K random read and random write on a dual socket (24 cores per socket) machine using the none schedulder is as follows: before patch: write (psync x 96 jobs) = 465 KIOPS read (libaio@qd=8 x 96 jobs) = 1361 KIOPS after patch: write (psync x 96 jobs) = 456 KIOPS read (libaio@qd=8 x 96 jobs) = 4096 KIOPS Write performance remains mostly unchanged but read performance is three times higher. Performance when using the mq-deadline scheduler is not changed by this patch as mq-deadline becomes the bottleneck for a multi-queue device. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
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| net | ||
| samples | ||
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| usr | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| 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.