From: Dmitry Bogdanov <d.bogdanov@yadro.com>
To: Mike Christie <michael.christie@oracle.com>
Cc: <bvanassche@acm.org>, <martin.petersen@oracle.com>,
<linux-scsi@vger.kernel.org>, <target-devel@vger.kernel.org>
Subject: Re: [PATCH v2 3/3] scsi: target: Move LUN stats to per CPU
Date: Wed, 17 Sep 2025 16:38:04 +0300 [thread overview]
Message-ID: <20250917133804.GF624@yadro.com> (raw)
In-Reply-To: <20250908231000.10777-4-michael.christie@oracle.com>
On Mon, Sep 08, 2025 at 06:05:56PM -0500, Mike Christie wrote:
>
> The atomic use in the main I/O path is causing perf issues when using
> higher performance backend devices and multiple queues (more than
> 10 when using vhost-scsi) like with this fio workload:
>
> [global]
> bs=4K
> iodepth=128
> direct=1
> ioengine=libaio
> group_reporting
> time_based
> runtime=120
> name=standard-iops
> rw=randread
> numjobs=16
> cpus_allowed=0-15
>
> To fix this issue, this moves the LUN stats to per CPU.
>
> Note: I forgot to include this patch with the delayed/ordered per CPU
> tracking and per device/device entry per CPU stats. With this patch you
> get the full 33% improvements when using fast backends, multiple queues
> and multiple IO submiters.
>
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
prev parent reply other threads:[~2025-09-17 13:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-08 23:05 [PATCH v2 0/3] target: RW/num_cmds stats improvements Mike Christie
2025-09-08 23:05 ` [PATCH v2 1/3] scsi: target: Fix lun/device R/W and total command stats Mike Christie
2025-09-17 13:47 ` Dmitry Bogdanov
2025-09-08 23:05 ` [PATCH v2 2/3] scsi: target: Create and use macro helpers for per CPU stats Mike Christie
2025-09-17 13:33 ` Dmitry Bogdanov
2025-09-08 23:05 ` [PATCH v2 3/3] scsi: target: Move LUN stats to per CPU Mike Christie
2025-09-09 15:36 ` Maurizio Lombardi
2025-09-17 13:38 ` Dmitry Bogdanov [this message]
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