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Date: Wed, 28 Jan 2015 13:50:28 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        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
Message-ID: <20150128045028.GB577@swordfish>
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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.

	-ss