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94f71c1606
I attached several backend devices in the same cache set, and produced lots of dirty data by running small rand I/O writes in a long time, then I continue run I/O in the others cached devices, and stopped a cached device, after a mean while, I register the stopped device again, I see the running I/O in the others cached devices dropped significantly, sometimes even jumps to zero. In currently code, bcache would traverse each keys and btree node to count the dirty data under read locker, and the writes threads can not get the btree write locker, and when there is a lot of keys and btree node in the registering device, it would last several seconds, so the write I/Os in others cached device are blocked and declined significantly. In this patch, when a device registering to a ache set, which exist others cached devices with running I/Os, we get the amount of dirty data of the device in an incremental way, and do not block other cached devices all the time. Patch v2: Rename some variables and macros name as Coly suggested. Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn> Signed-off-by: Coly Li <colyli@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.