* [PATCH] PCI: Allow scheduling to take place in proc_bus_pci_read()
@ 2021-08-15 15:08 Krzysztof Wilczyński
2021-08-20 21:23 ` Bjorn Helgaas
0 siblings, 1 reply; 2+ messages in thread
From: Krzysztof Wilczyński @ 2021-08-15 15:08 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: Bin Lai, Jiang Biao, linux-pci
PCI configuration space reads from the /proc/bus/pci for a particular
device, depending on the underlying hardware, can often take several
milliseconds to complete.
Thus, add a schedule point in proc_bus_pci_read() to reduce the maximum
latency.
A similar change has already been completed in the past for the sysfs
counterpart in the commit 2ce02a864ac1 ("PCI: Add schedule point in
pci_read_config()").
Link: https://lore.kernel.org/r/20200824052025.48362-1-benbjiang@tencent.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
---
drivers/pci/proc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index d32fbfc93ea9..cb18f8a13ab6 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -83,6 +83,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,
buf += 4;
pos += 4;
cnt -= 4;
+ cond_resched();
}
if (cnt >= 2) {
--
2.32.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] PCI: Allow scheduling to take place in proc_bus_pci_read()
2021-08-15 15:08 [PATCH] PCI: Allow scheduling to take place in proc_bus_pci_read() Krzysztof Wilczyński
@ 2021-08-20 21:23 ` Bjorn Helgaas
0 siblings, 0 replies; 2+ messages in thread
From: Bjorn Helgaas @ 2021-08-20 21:23 UTC (permalink / raw)
To: Krzysztof Wilczyński; +Cc: Bjorn Helgaas, Bin Lai, Jiang Biao, linux-pci
On Sun, Aug 15, 2021 at 03:08:24PM +0000, Krzysztof Wilczyński wrote:
> PCI configuration space reads from the /proc/bus/pci for a particular
> device, depending on the underlying hardware, can often take several
> milliseconds to complete.
>
> Thus, add a schedule point in proc_bus_pci_read() to reduce the maximum
> latency.
>
> A similar change has already been completed in the past for the sysfs
> counterpart in the commit 2ce02a864ac1 ("PCI: Add schedule point in
> pci_read_config()").
>
> Link: https://lore.kernel.org/r/20200824052025.48362-1-benbjiang@tencent.com
> Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Applied to pci/misc for v5.15, thanks!
I tweaked your subject line to match 2ce02a864ac1:
PCI: Add schedule point in proc_bus_pci_read()
> ---
> drivers/pci/proc.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
> index d32fbfc93ea9..cb18f8a13ab6 100644
> --- a/drivers/pci/proc.c
> +++ b/drivers/pci/proc.c
> @@ -83,6 +83,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf,
> buf += 4;
> pos += 4;
> cnt -= 4;
> + cond_resched();
> }
>
> if (cnt >= 2) {
> --
> 2.32.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-08-15 15:08 [PATCH] PCI: Allow scheduling to take place in proc_bus_pci_read() Krzysztof Wilczyński
2021-08-20 21:23 ` Bjorn Helgaas
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