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Message-ID: <c1358b840b3a4971aa35a25d8495c2c8953403ea.camel@unipv.it>
Date: Thu, 28 Nov 2019 08:46:57 +0100
From: Andrea Vai <andrea.vai@...pv.it>
To: "Schmid, Carsten" <Carsten_Schmid@...tor.com>,
Finn Thain <fthain@...egraphics.com.au>
Cc: Ming Lei <ming.lei@...hat.com>,
Damien Le Moal <Damien.LeMoal@....com>,
Alan Stern <stern@...land.harvard.edu>,
Jens Axboe <axboe@...nel.dk>,
Johannes Thumshirn <jthumshirn@...e.de>,
USB list <linux-usb@...r.kernel.org>,
SCSI development list <linux-scsi@...r.kernel.org>,
Himanshu Madhani <himanshu.madhani@...ium.com>,
Hannes Reinecke <hare@...e.com>,
Omar Sandoval <osandov@...com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Greg KH <gregkh@...uxfoundation.org>,
Hans Holmberg <Hans.Holmberg@....com>,
Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: AW: Slow I/O on USB media after commit
f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
Il giorno mer, 27/11/2019 alle 08.14 +0000, Schmid, Carsten ha
scritto:
> >
> > > Then I started another set of 100 trials and let them run
> tonight, and
> > > the first 10 trials were around 1000s, then gradually decreased
> to
> > > ~300s, and finally settled around 200s with some trials below
> 70-80s.
> > > This to say, times are extremely variable and for the first time
> I
> > > noticed a sort of "performance increase" with time.
> > >
> >
> > The sheer volume of testing (probably some terabytes by now) would
> > exercise the wear leveling algorithm in the FTL.
> >
> But with "old kernel" the copy operation still is "fast", as far as
> i understood.
> If FTL (e.g. wear leveling) would slow down, we would see that also
> in
> the old kernel, right?
>
> Andrea, can you confirm that the same device used with the old fast
> kernel is still fast today?
Yes, it is still fast. Just ran a 100 trials test and got an average
of 70 seconds with standard deviation = 6 seconds, aligned with the
past values of the same kernel.
Thanks,
Andrea
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