From: Bart Van Assche <bvanassche@acm.org>
To: Ming Lei <ming.lei@redhat.com>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
linux-scsi@vger.kernel.org,
"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
"Ewan D . Milne" <emilne@redhat.com>,
Hannes Reinecke <hare@suse.com>
Subject: Re: [PATCH 2/2] scsi: core: avoid to pre-allocate big chunk for sg list
Date: Tue, 23 Apr 2019 08:37:15 -0700 [thread overview]
Message-ID: <1556033835.161891.123.camel@acm.org> (raw)
In-Reply-To: <20190423103240.29864-3-ming.lei@redhat.com>
On Tue, 2019-04-23 at 18:32 +0800, Ming Lei wrote:
> #define SCSI_INLINE_PROT_SG_CNT 1
>
> +#define SCSI_INLINE_SG_CNT 2
So this patch inserts one kmalloc() and one kfree() call in the hot path
for every SCSI request with more than two elements in its scatterlist? Isn't
"2" too low? Or in other words, what is the performance impact of this patch
for a real-world workload?
Thanks,
Bart.
next prev parent reply other threads:[~2019-04-23 15:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 10:32 [PATCH 0/2] scis: core: avoid big pre-allocation for sg list Ming Lei
2019-04-23 10:32 ` [PATCH 1/2] scsi: core: avoid to pre-allocate big chunk for protection meta data Ming Lei
2019-04-23 15:33 ` Bart Van Assche
2019-04-24 0:46 ` Ming Lei
2019-04-23 10:32 ` [PATCH 2/2] scsi: core: avoid to pre-allocate big chunk for sg list Ming Lei
2019-04-23 15:37 ` Bart Van Assche [this message]
2019-04-24 7:52 ` Ming Lei
2019-04-24 15:24 ` James Bottomley
2019-04-24 15:32 ` Bart Van Assche
2019-04-24 15:37 ` Jens Axboe
2019-04-24 15:49 ` James Bottomley
2019-04-24 16:09 ` Bart Van Assche
2019-04-24 16:17 ` James Bottomley
2019-04-24 5:53 ` Christoph Hellwig
2019-04-24 8:41 ` Ming Lei
2019-04-24 14:38 ` Christoph Hellwig
2019-04-25 0:45 ` Ming Lei
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