RE: [linuxppc-release] [PATCH v2 4/4] fsl-dma: use spin_lock_bh to instead of spin_lock_irqsave

-----Original Message-----
From: Tabi Timur-B04825
Sent: Wednesday, July 11, 2012 11:01 PM
To: Liu Qiang-B32616
Cc: linux-crypto@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Vinod
Koul; herbert@gondor.hengli.com.au; Dan Williams; Li Yang-R58472;
davem@davemloft.net
Subject: Re: [linuxppc-release] [PATCH v2 4/4] fsl-dma: use spin_lock_bh
to instead of spin_lock_irqsave
=20
Qiang Liu wrote:

quoted

Use spin_lock_bh to instead of spin_lock_irqsave for improving

performance.
=20
Please provide some evidence that performance has improved, as well as an
explanation why it's okay to use spin_lock_bh, and why it's faster.

I compared my test result before and after this patch, write performance ca=
n
improved by 15%. I will send the latest patches sooner because of Ira's con=
cern.
I will give a complete description about the improvement of spin_lock_bh().

About your question, spin_lock_bh is used in the case of bottom/half as its
name, there is no need to protect a running/pending list with spin_lock_irq=
save.

Thanks.

--
Timur Tabi
Linux kernel developer at Freescale