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Date: Wed, 28 Jan 2015 13:58:55 +0900
From: Minchan Kim <minchan@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Jerome Marchand <jmarchan@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Nitin Gupta <ngupta@vflare.org>
Subject: Re: [PATCH 1/2] zram: free meta out of init_lock
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On Wed, Jan 28, 2015 at 01:50:28PM +0900, Sergey Senozhatsky wrote:
> On (01/28/15 13:07), Sergey Senozhatsky wrote:
> > On (01/28/15 12:53), Sergey Senozhatsky wrote:
> > > > So, I want to go with srcu. Do you agree? or another suggestion?
> > > 
> > > yes, I think we need to take a second look on srcu approach.
> > > 
> > 
> > ... or we can ask lockdep to stop false alarming us and leave it as is.
> > I wouldn't say that ->init_lock is so hard to understand.
> > just as an option.
> > 
> 
> so... returning back to barriers performance implications.
> 
> x86_64, lzo, 4 comp streams, 2G zram, ext4, mount -o rw,relatime,data=ordered
> 
>  ./iozone -t 3 -R -r 16K -s 60M -I +Z
> 
>        test           base          srcu
> "  Initial write " 1299639.75   1277621.03
> "        Rewrite " 2139387.50   2004663.94
> "           Read " 6193415.00   5091000.00
> "        Re-read " 6199050.38   4814297.88
> "   Reverse Read " 4693868.88   4367201.75
> "    Stride read " 4470633.75   4247550.00
> "    Random read " 5115339.50   4517352.75
> " Mixed workload " 4340747.06   3880517.31
> "   Random write " 1982369.75   1892456.25
> "         Pwrite " 1352550.22   1248667.78
> "          Pread " 2853150.06   2445154.41
> "         Fwrite " 2367397.81   2262384.56
> "          Fread " 8100746.50   7578071.75
> 
> not good.
> 

Oops, I never thought it could make mesurable performance.
I will investigate it.

Thanks a lot, Sergey!

> 	-ss

-- 
Kind regards,
Minchan Kim