Re: scsi-mq V2

From: Jens Axboe
Date: Thu Jul 10 2014 - 15:59:46 EST


On 2014-07-10 17:11, Jeff Moyer wrote:
Benjamin LaHaise <bcrl@xxxxxxxxx> writes:


[ 186.339064] ioctx_alloc: nr_events=-2 aio_max_nr=65536
[ 186.339065] ioctx_alloc: nr_events=-2 aio_max_nr=65536
[ 186.339067] ioctx_alloc: nr_events=-2 aio_max_nr=65536
[ 186.339068] ioctx_alloc: nr_events=-2 aio_max_nr=65536
[ 186.339069] ioctx_alloc: nr_events=-2 aio_max_nr=65536

Something is horribly wrong here. There is no way that value for nr_events
should be passed in to ioctx_alloc(). This implies that userland is calling
io_setup() with an impossibly large value for nr_events. Can you post the
actual diff for your fs/aio.c relative to linus' tree?


fio does exactly this! it passes INT_MAX.

That's correct, I had actually forgotten about this. It was a change made a few years back, in correlation with the aio optimizations posted then, basically telling aio to ignore that silly (and broken) user ring.

--
Jens Axboe

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