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[RFC,for-next,0/4] enable pcpu bio caching for IRQ I/O

Message ID cover.1666114003.git.asml.silence@gmail.com (mailing list archive)
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Series enable pcpu bio caching for IRQ I/O | expand

Message

Pavel Begunkov Oct. 18, 2022, 6:47 p.m. UTC 
This series implements bio pcpu caching for normal / IRQ-driven I/O
extending REQ_ALLOC_CACHE currently limited to iopoll. The allocation side
still only works from non-irq context, which is the reason it's not enabled
by default, but turning it on for other users (e.g. filesystems) is
as a matter of passing a flag.

t/io_uring with an Optane SSD setup showed +7% for batches of 32 requests
and +4.3% for batches of 8.

IRQ, 128/32/32, cache off
IOPS=59.08M, BW=28.84GiB/s, IOS/call=31/31
IOPS=59.30M, BW=28.96GiB/s, IOS/call=32/32
IOPS=59.97M, BW=29.28GiB/s, IOS/call=31/31
IOPS=59.92M, BW=29.26GiB/s, IOS/call=32/32
IOPS=59.81M, BW=29.20GiB/s, IOS/call=32/31

IRQ, 128/32/32, cache on
IOPS=64.05M, BW=31.27GiB/s, IOS/call=32/31
IOPS=64.22M, BW=31.36GiB/s, IOS/call=32/32
IOPS=64.04M, BW=31.27GiB/s, IOS/call=31/31
IOPS=63.16M, BW=30.84GiB/s, IOS/call=32/32

IRQ, 32/8/8, cache off
IOPS=50.60M, BW=24.71GiB/s, IOS/call=7/8
IOPS=50.22M, BW=24.52GiB/s, IOS/call=8/7
IOPS=49.54M, BW=24.19GiB/s, IOS/call=8/8
IOPS=50.07M, BW=24.45GiB/s, IOS/call=7/7
IOPS=50.46M, BW=24.64GiB/s, IOS/call=8/8

IRQ, 32/8/8, cache on
IOPS=51.39M, BW=25.09GiB/s, IOS/call=8/7
IOPS=52.52M, BW=25.64GiB/s, IOS/call=7/8
IOPS=52.57M, BW=25.67GiB/s, IOS/call=8/8
IOPS=52.58M, BW=25.67GiB/s, IOS/call=8/7
IOPS=52.61M, BW=25.69GiB/s, IOS/call=8/8

The main part is in patch 3. Would be great to take patch 1 separately
for 6.1 for extra safety.

Pavel Begunkov (4):
  bio: safeguard REQ_ALLOC_CACHE bio put
  bio: split pcpu cache part of bio_put into a helper
  block/bio: add pcpu caching for non-polling bio_put
  io_uring/rw: enable bio caches for IRQ rw

 block/bio.c   | 92 +++++++++++++++++++++++++++++++++++++++------------
 io_uring/rw.c |  3 +-
 2 files changed, 73 insertions(+), 22 deletions(-)

Comments

Pavel Begunkov Oct. 18, 2022, 7:33 p.m. UTC | #1 
On 10/18/22 19:47, Pavel Begunkov wrote:
> This series implements bio pcpu caching for normal / IRQ-driven I/O
> extending REQ_ALLOC_CACHE currently limited to iopoll. The allocation side
> still only works from non-irq context, which is the reason it's not enabled
> by default, but turning it on for other users (e.g. filesystems) is
> as a matter of passing a flag.

Ooops, wrong version, will resend


> t/io_uring with an Optane SSD setup showed +7% for batches of 32 requests
> and +4.3% for batches of 8.
> 
> IRQ, 128/32/32, cache off
> IOPS=59.08M, BW=28.84GiB/s, IOS/call=31/31
> IOPS=59.30M, BW=28.96GiB/s, IOS/call=32/32
> IOPS=59.97M, BW=29.28GiB/s, IOS/call=31/31
> IOPS=59.92M, BW=29.26GiB/s, IOS/call=32/32
> IOPS=59.81M, BW=29.20GiB/s, IOS/call=32/31
> 
> IRQ, 128/32/32, cache on
> IOPS=64.05M, BW=31.27GiB/s, IOS/call=32/31
> IOPS=64.22M, BW=31.36GiB/s, IOS/call=32/32
> IOPS=64.04M, BW=31.27GiB/s, IOS/call=31/31
> IOPS=63.16M, BW=30.84GiB/s, IOS/call=32/32
> 
> IRQ, 32/8/8, cache off
> IOPS=50.60M, BW=24.71GiB/s, IOS/call=7/8
> IOPS=50.22M, BW=24.52GiB/s, IOS/call=8/7
> IOPS=49.54M, BW=24.19GiB/s, IOS/call=8/8
> IOPS=50.07M, BW=24.45GiB/s, IOS/call=7/7
> IOPS=50.46M, BW=24.64GiB/s, IOS/call=8/8
> 
> IRQ, 32/8/8, cache on
> IOPS=51.39M, BW=25.09GiB/s, IOS/call=8/7
> IOPS=52.52M, BW=25.64GiB/s, IOS/call=7/8
> IOPS=52.57M, BW=25.67GiB/s, IOS/call=8/8
> IOPS=52.58M, BW=25.67GiB/s, IOS/call=8/7
> IOPS=52.61M, BW=25.69GiB/s, IOS/call=8/8
> 
> The main part is in patch 3. Would be great to take patch 1 separately
> for 6.1 for extra safety.
> 
> Pavel Begunkov (4):
>    bio: safeguard REQ_ALLOC_CACHE bio put
>    bio: split pcpu cache part of bio_put into a helper
>    block/bio: add pcpu caching for non-polling bio_put
>    io_uring/rw: enable bio caches for IRQ rw
> 
>   block/bio.c   | 92 +++++++++++++++++++++++++++++++++++++++------------
>   io_uring/rw.c |  3 +-
>   2 files changed, 73 insertions(+), 22 deletions(-)
>