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Re: [Qemu-devel] [PATCH v3 1/7] block: use 1 MB bounce buffers for crypt
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v3 1/7] block: use 1 MB bounce buffers for crypto instead of 16KB |
Date: |
Sat, 16 Sep 2017 18:25:19 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 2017-09-12 13:28, Daniel P. Berrange wrote:
> Using 16KB bounce buffers creates a significant performance
> penalty for I/O to encrypted volumes on storage which high
> I/O latency (rotating rust & network drives), because it
> triggers lots of fairly small I/O operations.
>
> On tests with rotating rust, and cache=none|directsync,
> write speed increased from 2MiB/s to 32MiB/s, on a par
> with that achieved by the in-kernel luks driver. With
> other cache modes the in-kernel driver is still notably
> faster because it is able to report completion of the
> I/O request before any encryption is done, while the
> in-QEMU driver must encrypt the data before completion.
>
> Reviewed-by: Eric Blake <address@hidden>
> Reviewed-by: Stefan Hajnoczi <address@hidden>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> block/crypto.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
Reviewed-by: Max Reitz <address@hidden>
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- [Qemu-devel] [PATCH v3 0/7] Misc improvements to crypto block driver, Daniel P. Berrange, 2017/09/12
- [Qemu-devel] [PATCH v3 2/7] crypto: expose encryption sector size in APIs, Daniel P. Berrange, 2017/09/12
- [Qemu-devel] [PATCH v3 3/7] block: fix data type casting for crypto payload offset, Daniel P. Berrange, 2017/09/12
- [Qemu-devel] [PATCH v3 1/7] block: use 1 MB bounce buffers for crypto instead of 16KB, Daniel P. Berrange, 2017/09/12
- Re: [Qemu-devel] [PATCH v3 1/7] block: use 1 MB bounce buffers for crypto instead of 16KB,
Max Reitz <=
- [Qemu-devel] [PATCH v3 4/7] block: don't use constant 512 as sector size in crypto driver, Daniel P. Berrange, 2017/09/12
- [Qemu-devel] [PATCH v3 5/7] block: convert crypto driver to bdrv_co_preadv|pwritev, Daniel P. Berrange, 2017/09/12
- [Qemu-devel] [PATCH v3 7/7] block: support passthrough of BDRV_REQ_FUA in crypto driver, Daniel P. Berrange, 2017/09/12