Re: Asynchronous scsi scanning

From: Satyam Sharma
Date: Thu May 17 2007 - 13:13:23 EST


Hi Matthew,

On 5/16/07, Matthew Wilcox <matthew@xxxxxx> wrote:
[...]
> /sys/module/scsi_mod/parameters/wait_for_async_scans (?)
> Doesn't really matter, but perhaps who created the sysfs namespace
> for scsi in /sys/module/scsi_mod/... could be the best person to suggest.

No, it does matter. Your suggestion doesn't work, because
/sys/module/scsi_mod/parameters/ belongs to the module code. To create
a new attribute there, you use the module_param() code -- and there's
no way to have code called when your parameter is changed.

Ok, thanks for pointing out that /sys/module/scsi_mod/parameters/wait...
is _wrong_. Could you suggest something that would be _right_?

> OK, I'll get really silly here myself. I don't want even that half a second
> of
> overhead when that module is being _built_ (during make modules), not
> the overhead of copying / installing at modules_install time.

You're claiming that 0.7 second (I just timed it on a 3 year old
laptop) *inconveniences* you?

...

On 5/16/07, Satyam Sharma <satyam.sharma@xxxxxxxxx> wrote:
OK, I'll get really silly here myself. ...

...

On 5/16/07, Satyam Sharma <satyam.sharma@xxxxxxxxx> wrote:
It's not _inconvenient_. Just that writing/building a module for accomplishing
something like that ... is just not _right_.

...

On 5/16/07, Satyam Sharma <satyam.sharma@xxxxxxxxx> wrote:
static int __init wait_scan_init(void)
{
scsi_complete_async_scans();
return 0;
/* BTW this could've been return scsi_complete_async_scans();
* I see scsi_complete_async_scans() never fails, but still. */
}
late_initcall(wait_scan_init);
... does _not_ deserve to be a module, and writing/building a module
for something like this (just to run a function in some kernel subsytem)
does not seem to be the proper way to solve the problem either.

...

This whole thing is such a tempest in a teapot. I really don't
understand why you care so much.

You're almost right here. But IMHO this is simply a case of
doing something in some kernel subsystem in a proper/better
way than it is being done presently.

Anyway, like I said on another thread, discussions here tend to be
most productive only over code, so I'll try and make a patch to do
this some other way.

Thanks,
Satyam
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