Messages in this thread | | | From | Paolo Valente <> | Subject | [PATCH BUGFIX 0/3] null_blk: fix throughout losses and hangs | Date | Mon, 2 Nov 2015 15:31:10 +0100 |
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Hi, while doing some tests with the null_blk device driver, we bumped into two problems: first, unjustified and in some cases high throughput losses; second, actual hangs. These problems seem to be the consequence of the combination of three causes, and this patchset introduces a fix for each of these causes. In particular, changes address: . an apparent flaw in the logic with which delayed completions are implemented: this flaw causes, with unlucky but non-pathological workloads, actual request-completion delays to become arbitrarily larger than the configured delay; . the missing restart of the device queue on the completion of a request in single-queue non-delayed mode; . the overflow of the request-delay parameter, when extremely high values are used (e.g., to spot bugs).
To avoid possible confusion, we stress that these fixes *do not* have anything to do with the problems highlighted in [1] (tests of the multiqueue xen-blkfront and xen-blkback modules with null_blk).
You can find more details in the patch descriptions.
Thanks, Paolo and Arianna
[1] https://lkml.org/lkml/2015/8/19/181
Arianna Avanzini (2): null_blk: guarantee device restart in all irq modes null_blk: change type of completion_nsec to unsigned long
Paolo Valente (1): null_blk: set a separate timer for each command
drivers/block/null_blk.c | 94 +++++++++++++++++------------------------------- 1 file changed, 33 insertions(+), 61 deletions(-)
-- 1.9.1
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