From: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
To: Finn Thain <fthain@telegraphics.com.au>
Cc: tanxiaofei <tanxiaofei@huawei.com>,
"jejb@linux.ibm.com" <jejb@linux.ibm.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxarm@openeuler.org" <linuxarm@openeuler.org>,
"linux-m68k@vger.kernel.org" <linux-m68k@vger.kernel.org>
Subject: RE: [Linuxarm] Re: [PATCH for-next 00/32] spin lock usage optimization for SCSI drivers
Date: Tue, 9 Feb 2021 05:33:55 +0000 [thread overview]
Message-ID: <6712a7f16b99489db2828098dc3e03b2@hisilicon.com> (raw)
In-Reply-To: <f0a3339d-b1db-6571-fa2f-6765e150eb9d@telegraphics.com.au>
> -----Original Message-----
> From: Finn Thain [mailto:fthain@telegraphics.com.au]
> Sent: Tuesday, February 9, 2021 6:06 PM
> To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>
> Cc: tanxiaofei <tanxiaofei@huawei.com>; jejb@linux.ibm.com;
> martin.petersen@oracle.com; linux-scsi@vger.kernel.org;
> linux-kernel@vger.kernel.org; linuxarm@openeuler.org;
> linux-m68k@vger.kernel.org
> Subject: RE: [Linuxarm] Re: [PATCH for-next 00/32] spin lock usage optimization
> for SCSI drivers
>
> On Tue, 9 Feb 2021, Song Bao Hua (Barry Song) wrote:
>
> > > -----Original Message-----
> > > From: Finn Thain [mailto:fthain@telegraphics.com.au]
> > > Sent: Monday, February 8, 2021 8:57 PM
> > > To: tanxiaofei <tanxiaofei@huawei.com>
> > > Cc: jejb@linux.ibm.com; martin.petersen@oracle.com;
> > > linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org;
> > > linuxarm@openeuler.org
> > > Subject: [Linuxarm] Re: [PATCH for-next 00/32] spin lock usage optimization
> > > for SCSI drivers
> > >
> > > On Sun, 7 Feb 2021, Xiaofei Tan wrote:
> > >
> > > > Replace spin_lock_irqsave with spin_lock in hard IRQ of SCSI drivers.
> > > > There are no function changes, but may speed up if interrupt happen too
> > > > often.
> > >
> > > This change doesn't necessarily work on platforms that support nested
> > > interrupts.
> > >
> > > Were you able to measure any benefit from this change on some other
> > > platform?
> >
> > I think the code disabling irq in hardIRQ is simply wrong.
> > Since this commit
> >
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/
> ?id=e58aa3d2d0cc
> > genirq: Run irq handlers with interrupts disabled
> >
> > interrupt handlers are definitely running in a irq-disabled context
> > unless irq handlers enable them explicitly in the handler to permit
> > other interrupts.
> >
>
> Repeating the same claim does not somehow make it true. If you put your
Sorry for I didn't realize xiaofei had replied.
> claim to the test, you'll see that that interrupts are not disabled on
> m68k when interrupt handlers execute.
Sounds like an implementation issue of m68k since IRQF_DISABLED has
been totally removed.
>
> The Interrupt Priority Level (IPL) can prevent any given irq handler from
> being re-entered, but an irq with a higher priority level may be handled
> during execution of a lower priority irq handler.
>
We used to have IRQF_DISABLED to support so-called "fast interrupt" to avoid
this. But the concept has been totally removed. That is interesting if m68k
still has this issue.
> sonic_interrupt() uses an irq lock within an interrupt handler to avoid
> issues relating to this. This kind of locking may be needed in the drivers
> you are trying to patch. Or it might not. Apparently, no-one has looked.
Thanks
Barry
next prev parent reply other threads:[~2021-02-09 5:35 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-07 11:36 [PATCH for-next 00/32] spin lock usage optimization for SCSI drivers Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 01/32] scsi: 53c700: Replace spin_lock_irqsave with spin_lock in hard IRQ Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 02/32] scsi: ipr: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 03/32] scsi: lpfc: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 04/32] scsi: qla4xxx: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 05/32] scsi: BusLogic: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 06/32] scsi: a100u2w: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 07/32] scsi: a2091: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 08/32] scsi: a3000: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 09/32] scsi: aha1740: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 10/32] scsi: bfa: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 11/32] scsi: esp_scsi: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 12/32] scsi: gvp11: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 13/32] scsi: hptiop: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 14/32] scsi: ibmvscsi: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 15/32] scsi: initio: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 16/32] scsi: megaraid: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 17/32] scsi: mac53c94: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 18/32] scsi: mesh: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 19/32] scsi: mvumi: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 20/32] scsi: myrb: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 21/32] scsi: myrs: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 22/32] scsi: ncr53c8xx: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 23/32] scsi: nsp32: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 24/32] scsi: pmcraid: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 25/32] scsi: pcmcia: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 26/32] scsi: qlogicfas408: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 27/32] scsi: qlogicpti: " Xiaofei Tan
2021-02-07 11:36 ` [PATCH for-next 28/32] scsi: sgiwd93: " Xiaofei Tan
2021-02-07 11:37 ` [PATCH for-next 29/32] scsi: stex: " Xiaofei Tan
2021-02-07 11:37 ` [PATCH for-next 30/32] scsi: vmw_pvscsi: " Xiaofei Tan
2021-02-07 11:37 ` [PATCH for-next 31/32] scsi: wd719x: " Xiaofei Tan
2021-02-07 11:37 ` [PATCH for-next 32/32] scsi: advansys: " Xiaofei Tan
2021-02-08 7:57 ` [PATCH for-next 00/32] spin lock usage optimization for SCSI drivers Finn Thain
2021-02-09 1:48 ` [Linuxarm] " Song Bao Hua (Barry Song)
2021-02-09 5:06 ` Finn Thain
2021-02-09 5:33 ` Song Bao Hua (Barry Song) [this message]
2021-02-10 0:28 ` Finn Thain
2021-02-10 0:37 ` Song Bao Hua (Barry Song)
2021-02-10 4:14 ` Finn Thain
2021-02-09 5:46 ` Song Bao Hua (Barry Song)
2021-02-10 4:16 ` Finn Thain
2021-02-10 5:14 ` Song Bao Hua (Barry Song)
2021-02-10 21:06 ` Finn Thain
2021-02-10 21:28 ` Song Bao Hua (Barry Song)
2021-02-10 22:34 ` Finn Thain
2021-02-10 23:49 ` Song Bao Hua (Barry Song)
2021-02-11 1:11 ` Finn Thain
2021-02-11 3:02 ` Song Bao Hua (Barry Song)
2021-02-11 23:58 ` Finn Thain
2021-02-12 0:21 ` Song Bao Hua (Barry Song)
2021-02-18 7:12 ` Xiaofei Tan
2021-02-20 5:18 ` Finn Thain
2021-02-22 2:04 ` Song Bao Hua (Barry Song)
2021-02-23 5:25 ` Finn Thain
2021-02-23 5:47 ` Song Bao Hua (Barry Song)
2021-02-24 5:20 ` Finn Thain
2021-02-24 10:50 ` Song Bao Hua (Barry Song)
2021-02-25 7:07 ` Finn Thain
2021-02-09 2:00 ` tanxiaofei
2021-02-09 5:11 ` Finn Thain
2021-02-24 9:41 ` Geert Uytterhoeven
2021-02-25 2:37 ` [Linuxarm] " Xiaofei Tan
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