- 07 12月, 2017 1 次提交
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由 Omar Sandoval 提交于
Commit 8cf46660 ("kyber: fix hang on domain token wait queue") fixed a hang caused by leaving wait entries on the domain token wait queue after the __sbitmap_queue_get() retry succeeded, making that wait entry a "dud" which won't in turn wake more entries up. However, we can also get a dud entry if kyber_get_domain_token() fails once but is then called again and succeeds. This can happen if the hardware queue is rerun for some other reason, or, more likely, kyber_dispatch_request() tries the same domain twice. The fix is to remove our entry from the wait queue whenever we successfully get a token. The only complication is that we might be on one of many wait queues in the struct sbitmap_queue, but that's easily fixed by remembering which wait queue we were put on. While we're here, only initialize the wait queue entry once instead of on every wait, and use spin_lock_irq() instead of spin_lock_irqsave(), since this is always called from process context with irqs enabled. Signed-off-by: NOmar Sandoval <osandov@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
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- 01 11月, 2017 1 次提交
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由 Ming Lei 提交于
There may be request in sw queue, and not fetched to domain queue yet, so check it in kyber_has_work(). Signed-off-by: NMing Lei <ming.lei@redhat.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
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- 18 10月, 2017 1 次提交
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由 Omar Sandoval 提交于
When we're getting a domain token, if we fail to get a token on our first attempt, we put the current hardware queue on a wait queue and then try again just in case a token was freed after our initial attempt but before we got on the wait queue. If this second attempt succeeds, we currently leave the hardware queue on the wait queue. Usually this is okay; we'll just run the hardware queue one extra time when another token is freed. However, if the hardware queue doesn't have any other requests waiting, then when it it gets the extra wakeup, it won't have anything to free and therefore won't wake up any other hardware queues. If tokens are limited, then we won't make forward progress and the device will hang. Reported-by: NBin Zha <zhabin.zb@alibaba-inc.com> Signed-off-by: NOmar Sandoval <osandov@fb.com> Signed-off-by: NJens Axboe <axboe@kernel.dk>
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- 20 6月, 2017 2 次提交
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由 Ingo Molnar 提交于
So I've noticed a number of instances where it was not obvious from the code whether ->task_list was for a wait-queue head or a wait-queue entry. Furthermore, there's a number of wait-queue users where the lists are not for 'tasks' but other entities (poll tables, etc.), in which case the 'task_list' name is actively confusing. To clear this all up, name the wait-queue head and entry list structure fields unambiguously: struct wait_queue_head::task_list => ::head struct wait_queue_entry::task_list => ::entry For example, this code: rqw->wait.task_list.next != &wait->task_list ... is was pretty unclear (to me) what it's doing, while now it's written this way: rqw->wait.head.next != &wait->entry ... which makes it pretty clear that we are iterating a list until we see the head. Other examples are: list_for_each_entry_safe(pos, next, &x->task_list, task_list) { list_for_each_entry(wq, &fence->wait.task_list, task_list) { ... where it's unclear (to me) what we are iterating, and during review it's hard to tell whether it's trying to walk a wait-queue entry (which would be a bug), while now it's written as: list_for_each_entry_safe(pos, next, &x->head, entry) { list_for_each_entry(wq, &fence->wait.head, entry) { Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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由 Ingo Molnar 提交于
Rename: wait_queue_t => wait_queue_entry_t 'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue", but in reality it's a queue *entry*. The 'real' queue is the wait queue head, which had to carry the name. Start sorting this out by renaming it to 'wait_queue_entry_t'. This also allows the real structure name 'struct __wait_queue' to lose its double underscore and become 'struct wait_queue_entry', which is the more canonical nomenclature for such data types. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: NIngo Molnar <mingo@kernel.org>
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- 19 6月, 2017 2 次提交
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由 Christoph Hellwig 提交于
This patch makes sure we always allocate requests in the core blk-mq code and use a common prepare_request method to initialize them for both mq I/O schedulers. For Kyber and additional limit_depth method is added that is called before allocating the request. Also because none of the intializations can really fail the new method does not return an error - instead the bfq finish method is hardened to deal with the no-IOC case. Last but not least this removes the abuse of RQF_QUEUE by the blk-mq scheduling code as RQF_ELFPRIV is all that is needed now. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@kernel.dk>
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由 Christoph Hellwig 提交于
No need to have two different callouts of bfq vs kyber. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@kernel.dk>
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- 04 5月, 2017 1 次提交
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由 Omar Sandoval 提交于
Expose the domain token pools, asynchronous sbitmap depth, domain request lists, and batching state. Signed-off-by: NOmar Sandoval <osandov@fb.com> Reviewed-by: NHannes Reinecke <hare@suse.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 21 4月, 2017 1 次提交
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由 Stephen Bates 提交于
In order to allow for filtering of IO based on some other properties of the request than direction we allow the bucket function to return an int. If the bucket callback returns a negative do no count it in the stats accumulation. Signed-off-by: NStephen Bates <sbates@raithlin.com> Fixed up Kyber scheduler stat callback. Signed-off-by: NJens Axboe <axboe@fb.com>
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- 15 4月, 2017 1 次提交
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由 Omar Sandoval 提交于
The Kyber I/O scheduler is an I/O scheduler for fast devices designed to scale to multiple queues. Users configure only two knobs, the target read and synchronous write latencies, and the scheduler tunes itself to achieve that latency goal. The implementation is based on "tokens", built on top of the scalable bitmap library. Tokens serve as a mechanism for limiting requests. There are two tiers of tokens: queueing tokens and dispatch tokens. A queueing token is required to allocate a request. In fact, these tokens are actually the blk-mq internal scheduler tags, but the scheduler manages the allocation directly in order to implement its policy. Dispatch tokens are device-wide and split up into two scheduling domains: reads vs. writes. Each hardware queue dispatches batches round-robin between the scheduling domains as long as tokens are available for that domain. These tokens can be used as the mechanism to enable various policies. The policy Kyber uses is inspired by active queue management techniques for network routing, similar to blk-wbt. The scheduler monitors latencies and scales the number of dispatch tokens accordingly. Queueing tokens are used to prevent starvation of synchronous requests by asynchronous requests. Various extensions are possible, including better heuristics and ionice support. The new scheduler isn't set as the default yet. Signed-off-by: NOmar Sandoval <osandov@fb.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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