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* blkio-throttle: Fix possible multiplication overflow in iops calculationsVivek Goyal2010-10-011-1/+15
| | | | | | | | | | | | | | o User can specify max iops value of 32bit (UINT_MAX), through cgroup interface. If a user has specified say 4294967294 (UNIT_MAX - 2), then on 32bit platform, following multiplication can overflow. io_allowed = (tg->iops[rw] * jiffy_elapsed_rnd) o Explicitly cast the multiplication to 64bit and then perform division and then check whether result is still great then UNINT_MAX. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio-throttle: There is no need to convert jiffies to milli secondsVivek Goyal2010-10-011-4/+3
| | | | | | | | o Do not convert jiffies to mili seconds as it is not required. Just work with jiffies and HZ. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio-throttle: Fix link failure failure on i386Vivek Goyal2010-10-011-6/+10
| | | | | | | | | | | | | | | | | o Randy Dunlap reported following linux-next failure. This patch fixes it. on i386: blk-throttle.c:(.text+0x1abb8): undefined reference to `__udivdi3' blk-throttle.c:(.text+0x1b1dc): undefined reference to `__udivdi3' o bytes_per_second interface is 64bit and I was continuing to do 64 bit division even on 32bit platform without help of special macros/functions hence the failure. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio: Recalculate the throttled bio dispatch time upon throttle limit changeVivek Goyal2010-10-011-18/+116
| | | | | | | | | | | | | | | | | | | | | | | | o Currently any cgroup throttle limit changes are processed asynchronousy and the change does not take affect till a new bio is dispatched from same group. o It might happen that a user sets a redicuously low limit on throttling. Say 1 bytes per second on reads. In such cases simple operations like mount a disk can wait for a very long time. o Once bio is throttled, there is no easy way to come out of that wait even if user increases the read limit later. o This patch fixes it. Now if a user changes the cgroup limits, we recalculate the bio dispatch time according to new limits. o Can't take queueu lock under blkcg_lock, hence after the change I wake up the dispatch thread again which recalculates the time. So there are some variables being synchronized across two threads without lock and I had to make use of barriers. Hoping I have used barriers correctly. Any review of memory barrier code especially will help. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio: Add root group to td->tg_listVivek Goyal2010-10-011-4/+13
| | | | | | | | | | | | | | o Currently all the dynamically allocated groups, except root grp is added to td->tg_list. This was not a problem so far but in next patch I will travel through td->tg_list to process any updates of limits on the group. If root group is not in tg_list, then root group's updates are not processed. o It is better to root group also to tg_list instead of doing special processing for it during limit updates. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio: Implementation of IOPS limit logicVivek Goyal2010-09-161-37/+127
| | | | | | | o core logic of implementing IOPS throttling. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* blkio: Core implementation of throttle policyVivek Goyal2010-09-161-0/+909
o Actual implementation of throttling policy in block layer. Currently it implements READ and WRITE bytes per second throttling logic. IOPS throttling comes in later patches. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>