- 18 12月, 2009 2 次提交
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由 Vivek Goyal 提交于
o Currently code does not seem to be using cfqd->nr_groups. Get rid of it. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Reviewed-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o allow_merge() already checks if submitting task is pointing to same cfqq as rq has been queued in. If everything is fine, we should not be having a task in one cgroup and having a pointer to cfqq in other cgroup. Well I guess in some situations it can happen and that is, when a random IO queue has been moved into root cgroup for group_isolation=0. In this case, tasks's cgroup/group is different from where actually cfqq is, but this is intentional and in this case merging should be allowed. The second situation is where due to close cooperator patches, multiple processes can be sharing a cfqq. If everything implemented right, we should not end up in a situation where tasks from different processes in different groups are sharing the same cfqq as we allow merging of cooperating queues only if they are in same group. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Reviewed-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 15 12月, 2009 1 次提交
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由 Gui Jianfeng 提交于
When a group is resumed, if it doesn't have workload slice left, we should set workload_expires as expired. Otherwise, we might start from where we left in previous group by error. Thanks the idea from Corrado. Signed-off-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 11 12月, 2009 1 次提交
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由 Vivek Goyal 提交于
I think my previous patch introduced a bug which can lead to CFQ hitting BUG_ON(). The offending commit in for-2.6.33 branch is. commit 7667aa06 Author: Vivek Goyal <vgoyal@redhat.com> Date: Tue Dec 8 17:52:58 2009 -0500 cfq-iosched: Take care of corner cases of group losing share due to deletion While doing some stress testing on my box, I enountered following. login: [ 3165.148841] BUG: scheduling while atomic: swapper/0/0x10000100 [ 3165.149821] Modules linked in: cfq_iosched dm_multipath qla2xxx igb scsi_transport_fc dm_snapshot [last unloaded: scsi_wait_scan] [ 3165.149821] Pid: 0, comm: swapper Not tainted 2.6.32-block-for-33-merged-new #3 [ 3165.149821] Call Trace: [ 3165.149821] <IRQ> [<ffffffff8103fab8>] __schedule_bug+0x5c/0x60 [ 3165.149821] [<ffffffff8103afd7>] ? __wake_up+0x44/0x4d [ 3165.149821] [<ffffffff8153a979>] schedule+0xe3/0x7bc [ 3165.149821] [<ffffffff8103a796>] ? cpumask_next+0x1d/0x1f [ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e [cfq_iosched] [ 3165.149821] [<ffffffff810422d8>] __cond_resched+0x2a/0x35 [ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e [cfq_iosched] [ 3165.149821] [<ffffffff8153b1ee>] _cond_resched+0x2c/0x37 [ 3165.149821] [<ffffffff8100e2db>] is_valid_bugaddr+0x16/0x2f [ 3165.149821] [<ffffffff811e4161>] report_bug+0x18/0xac [ 3165.149821] [<ffffffff8100f1fc>] die+0x39/0x63 [ 3165.149821] [<ffffffff8153cde1>] do_trap+0x11a/0x129 [ 3165.149821] [<ffffffff8100d470>] do_invalid_op+0x96/0x9f [ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e [cfq_iosched] [ 3165.149821] [<ffffffff81034b4d>] ? enqueue_task+0x5c/0x67 [ 3165.149821] [<ffffffff8103ae83>] ? task_rq_unlock+0x11/0x13 [ 3165.149821] [<ffffffff81041aae>] ? try_to_wake_up+0x292/0x2a4 [ 3165.149821] [<ffffffff8100c935>] invalid_op+0x15/0x20 [ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e [cfq_iosched] [ 3165.149821] [<ffffffff810df5a6>] ? virt_to_head_page+0xe/0x2f [ 3165.149821] [<ffffffff811d8c2a>] blk_peek_request+0x191/0x1a7 [ 3165.149821] [<ffffffff811e5b8d>] ? kobject_get+0x1a/0x21 [ 3165.149821] [<ffffffff812c8d4c>] scsi_request_fn+0x82/0x3df [ 3165.149821] [<ffffffff8110b2de>] ? bio_fs_destructor+0x15/0x17 [ 3165.149821] [<ffffffff810df5a6>] ? virt_to_head_page+0xe/0x2f [ 3165.149821] [<ffffffff811d931f>] __blk_run_queue+0x42/0x71 [ 3165.149821] [<ffffffff811d9403>] blk_run_queue+0x26/0x3a [ 3165.149821] [<ffffffff812c8761>] scsi_run_queue+0x2de/0x375 [ 3165.149821] [<ffffffff812b60ac>] ? put_device+0x17/0x19 [ 3165.149821] [<ffffffff812c92d7>] scsi_next_command+0x3b/0x4b [ 3165.149821] [<ffffffff812c9b9f>] scsi_io_completion+0x1c9/0x3f5 [ 3165.149821] [<ffffffff812c3c36>] scsi_finish_command+0xb5/0xbe I think I have hit following BUG_ON() in cfq_dispatch_request(). BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); Please find attached the patch to fix it. I have done some stress testing with it and have not seen it happening again. o We should wait on a queue even after slice expiry only if it is empty. If queue is not empty then continue to expire it. o If we decide to keep the queue then make cfqq=NULL. Otherwise select_queue() will return a valid cfqq and cfq_dispatch_request() can hit following BUG_ON(). BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)) Reviewed-by: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 10 12月, 2009 2 次提交
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由 Gui Jianfeng 提交于
Remove wait_request flag when idle time is being deleted, otherwise it'll hit this path every time when a request is enqueued. Signed-off-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Corrado Zoccolo 提交于
Added a comment to explain the initialization of last_delayed_sync. Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com> Acked-by: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 09 12月, 2009 4 次提交
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由 Vivek Goyal 提交于
If there is a sequential reader running in a group, we wait for next request to come in that group after slice expiry and once new request is in, we expire the queue. Otherwise we delete the group from service tree and group looses its fair share. So far I was marking a queue as wait_busy if it had consumed its slice and it was last queue in the group. But this condition did not cover following two cases. 1.If a request completed and slice has not expired yet. Next request comes in and is dispatched to disk. Now select_queue() hits and slice has expired. This group will be deleted. Because request is still in the disk, this queue will never get a chance to wait_busy. 2.If request completed and slice has not expired yet. Before next request comes in (delay due to think time), select_queue() hits and expires the queue hence group. This queue never got a chance to wait busy. Gui was hitting the boundary condition 1 and not getting fairness numbers proportional to weight. This patch puts the checks for above two conditions and improves the fairness numbers for sequential workload on rotational media. Check in select_queue() takes care of case 1 and additional check in should_wait_busy() takes care of case 2. Reported-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Get rid of wait_busy_done flag. This flag only tells we were doing wait busy on a queue and that queue got request so expire it. That information can easily be obtained by (cfq_cfqq_wait_busy() && queue_is_not_empty). So remove this flag and keep code simple. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Gui Jianfeng 提交于
It doesn't make any sense to try to find out a close cooperating queue if current cfqq is the only one in the group. Signed-off-by: NGui Jianfeng <guijianfeng@cn.fujitsu.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Corrado Zoccolo 提交于
The introduction of ramp-up formula for async queue depths has slowed down dirty page reclaim, by reducing async write performance. This patch makes sure the formula kicks in only when sync request was recently delayed. Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 08 12月, 2009 1 次提交
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由 Vivek Goyal 提交于
Fix a crash during boot reported by Jeff Moyer. Fix the issue of accessing cfqq after freeing it. Reported-by: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Reviewed-by: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NJens Axboe <axboe@carl.(none)>
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- 06 12月, 2009 1 次提交
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由 Jens Axboe 提交于
After the merge of the IO controller patches, booting on my megaraid box ran much slower. Vivek Goyal traced it down to megaraid discovery creating tons of devices, each suffering a grace period when they later kill that queue (if no device is found). So lets use call_rcu() to batch these deferred frees, instead of taking the grace period hit for each one. Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 04 12月, 2009 23 次提交
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由 Vivek Goyal 提交于
o One of the goals of block IO controller is that it should be able to support mulitple io control policies, some of which be operational at higher level in storage hierarchy. o To begin with, we had one io controlling policy implemented by CFQ, and I hard coded the CFQ functions called by blkio. This created issues when CFQ is compiled as module. o This patch implements a basic dynamic io controlling policy registration functionality in blkio. This is similar to elevator functionality where ioschedulers register the functions dynamically. o Now in future, when more IO controlling policies are implemented, these can dynakically register with block IO controller. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o blkio controller is inside the kernel and cfq makes use of interfaces exported by blkio. CFQ can be a module too, hence export symbols used by CFQ. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Shaohua Li 提交于
cfq_arm_slice_timer() has logic to disable idle window for SSD device. The same thing should be done at cfq_select_queue() too, otherwise we will still see idle window. This makes the nonrot check logic consistent in cfq. Tests in a intel SSD with low_latency knob close, below patch can triple disk thoughput for muti-thread sequential read. Signed-off-by: NShaohua Li <shaohua.li@intel.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Jens Axboe 提交于
They should not be declared inside some other file that's not related to CFQ. Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o rq_noidle() is supposed to tell cfq that do not expect a request after this one, hence don't idle. But this does not seem to work very well. For example for direct random readers, rq_noidle = 1 but there is next request coming after this. Not idling, leads to a group not getting its share even if group_isolation=1. o The right solution for this issue is to scan the higher layers and set right flag (WRITE_SYNC or WRITE_ODIRECT). For the time being, this single line fix helps. This should not have any significant impact when we are not using cgroups. I will later figure out IO paths in higher layer and fix it. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o If a group is running only a random reader, then it will not have enough traffic to keep disk busy and we will reduce overall throughput. This should result in better latencies for random reader though. If we don't idle on random reader service tree, then this random reader will experience large latencies if there are other groups present in system with sequential readers running in these. o One solution suggested by corrado is that by default keep the random readers or sync-noidle workload in root group so that during one dispatch round we idle only once on sync-noidle tree. This means that all the sync-idle workload queues will be in their respective group and we will see service differentiation in those but not on sync-noidle workload. o Provide a tunable group_isolation. If set, this will make sure that even sync-noidle queues go in their respective group and we wait on these. This provides stronger isolation between groups but at the expense of throughput if group does not have enough traffic to keep the disk busy. o By default group_isolation = 0 Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Async queues are not per group. Instead these are system wide and maintained in root group. Hence their workload slice length should be calculated based on total number of queues in the system and not just queues in the root group. o As root group's default weight is 1000, make sure to charge async queue more in terms of vtime so that it does not get more time on disk because root group has higher weight. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o If a queue consumes its slice and then gets deleted from service tree, its associated group will also get deleted from service tree if this was the only queue in the group. That will make group loose its share. o For the queues on which we have idling on and if these have used their slice, wait a bit for these queues to get backlogged again and then expire these queues so that group does not loose its share. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Propagate blkio cgroup weight updation to associated cfq groups. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o If a task changes cgroup, drop reference to the cfqq associated with io context and set cfqq pointer stored in ioc to NULL so that upon next request arrival we will allocate a new queue in new group. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Do not allow following three operations across groups for isolation. - selection of co-operating queues - preemtpions across groups - request merging across groups. o Async queues are currently global and not per group. Allow preemption of an async queue if a sync queue in other group gets backlogged. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Export disk time and sector used by a group to user space through cgroup interface. o Also export a "dequeue" interface to cgroup which keeps track of how many a times a group was deleted from service tree. Helps in debugging. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Some debugging aids for CFQ. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o One can choose to change elevator or delete a cgroup. Implement group reference counting so that both elevator exit and cgroup deletion can take place gracefully. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NNauman Rafique <nauman@google.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Determine the cgroup IO submitting task belongs to and create the cfq group if it does not exist already. o Also link cfqq and associated cfq group. o Currently all async IO is mapped to root group. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o This patch introduces the functionality to do the accounting of group time when a queue expires. This time used decides which is the group to go next. o Also introduce the functionlity to save and restore the workload type context with-in group. It might happen that once we expire the cfq queue and group, a different group will schedule in and we will lose the context of the workload type. Hence save and restore it upon queue expiry. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o So far we had 300ms soft target latency system wide. Now with the introduction of cfq groups, divide that latency by number of groups so that one can come up with group target latency which will be helpful in determining the workload slice with-in group and also the dynamic slice length of the cfq queue. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Bring in the per cfq group weight and how vdisktime is calculated for the group. Also bring in the functionality of updating the min_vdisktime of the group service tree. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o So far we just had one cfq_group in cfq_data. To create space for more than one cfq_group, we need to have a service tree of groups where all the groups can be queued if they have active cfq queues backlogged in these. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Currently cfqq deletes a queue from service tree if it is empty (even if we might idle on the queue). This patch keeps the queue on service tree hence associated group remains on the service tree until we decide that we are not going to idle on the queue and expire it. o This just helps in time accounting for queue/group and in implementation of rest of the patches. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o Implement a macro to traverse each service tree in the group. This avoids usage of double for loop and special condition for idle tree 4 times. o Macro is little twisted because of special handling of idle class service tree. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o This patch introduce the notion of cfq groups. Soon we will can have multiple groups of different weights in the system. o Various service trees (prioclass and workload type trees), will become per cfq group. So hierarchy looks as follows. cfq_groups | workload type | cfq queue o When an scheduling decision has to be taken, first we select the cfq group then workload with-in the group and then cfq queue with-in the workload type. o This patch just makes various workload service tree per cfq group and introduce the function to be able to choose a group for scheduling. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Vivek Goyal 提交于
o must_dispatch flag should be set only if we decided not to run the queue and dispatch the request. Signed-off-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 03 12月, 2009 1 次提交
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由 Shaohua Li 提交于
Since commit 2f5cb738, each queue can send up to 4 * 4 requests if only one queue exists. I wonder why we have such limit. Device supports tag can send more requests. For example, AHCI can send 31 requests. Test (direct aio randread) shows the limits reduce about 4% disk thoughput. On the other hand, since we send one request one time, if other queue pop when current is sending more than cfq_quantum requests, current queue will stop send requests soon after one request, so sounds there is no big latency. Signed-off-by: NShaohua Li <shaohua.li@intel.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 30 11月, 2009 1 次提交
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由 Jens Axboe 提交于
This reverts commit 3586e917. Corrado Zoccolo <czoccolo@gmail.com> correctly points out, that we need consistency of rb_key offset across groups. This means we cannot properly use the per-service_tree service count. Revert this change. Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 26 11月, 2009 3 次提交
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由 Corrado Zoccolo 提交于
Idling logic was disabled in some corner cases, leading to unfair share for noidle queues. * the idle timer was not armed if there were other requests in the driver. unfortunately, those requests could come from other workloads, or queues for which we don't enable idling. So we will check only pending requests from the active queue * rq_noidle check on no-idle queue could disable the end of tree idle if the last completed request was rq_noidle. Now, we will disable that idle only if all the queues served in the no-idle tree had rq_noidle requests. Reported-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com> Acked-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Corrado Zoccolo 提交于
Seeky sync queues with large depth can gain unfairly big share of disk time, at the expense of other seeky queues. This patch ensures that idling will be enabled for queues with I/O depth at least 4, and small think time. The decision to enable idling is sticky, until an idle window times out without seeing a new request. The reasoning behind the decision is that, if an application is using large I/O depth, it is already optimized to make full utilization of the hardware, and therefore we reserve a slice of exclusive use for it. Reported-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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由 Corrado Zoccolo 提交于
An incoming no-idle queue should preempt the active no-idle queue only if the active queue is idling due to service tree empty. Previous code was buggy in two ways: * it relied on service_tree field to be set on the active queue, while it is not set when the code is idling for a new request * it didn't check for the service tree empty condition, so could lead to LIFO behaviour if multiple queues with depth > 1 were preempting each other on an non-NCQ device. Reported-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com> Acked-by: NVivek Goyal <vgoyal@redhat.com> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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