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From: Al Viro <viro@zeniv.linux.org.uk>
To: kernel test robot <rong.a.chen@intel.com>
Cc: David Howells <dhowells@redhat.com>,
	Hugh Dickins <hughd@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, lkp@01.org
Subject: Re: [vfs]  8bb3c61baf:  vm-scalability.median -23.7% regression
Date: Sun, 8 Sep 2019 22:46:01 +0100	[thread overview]
Message-ID: <20190908214601.GC1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190903084122.GH15734@shao2-debian>

On Tue, Sep 03, 2019 at 04:41:22PM +0800, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed a -23.7% regression of vm-scalability.median due to commit:
> 
> 
> commit: 8bb3c61bafa8c1cd222ada602bb94ff23119e738 ("vfs: Convert ramfs, shmem, tmpfs, devtmpfs, rootfs to use the new mount API")
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/viro/vfs.git work.mount
> 
> in testcase: vm-scalability
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 128G memory
> with following parameters:
> 
> 	runtime: 300s
> 	size: 16G
> 	test: shm-pread-rand
> 	cpufreq_governor: performance
> 	ucode: 0xb000036

That thing loses size=... option.  Both size= and nr_blocks= affect the
same thing (->max_blocks), but the parser keeps track of the options
it has seen and applying the parsed data to superblock checks only
whether nr_blocks= had been there.  IOW, size= gets parsed, but the
result goes nowhere.

I'm not sure whether it's better to fix the patch up or redo it from
scratch - it needs to be carved up anyway and it's highly non-transparent,
so I'm probably going to replace the damn thing entirely with something
that would be easier to follow.

WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: lkp@lists.01.org
Subject: Re: [vfs] 8bb3c61baf: vm-scalability.median -23.7% regression
Date: Sun, 08 Sep 2019 22:46:01 +0100	[thread overview]
Message-ID: <20190908214601.GC1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190903084122.GH15734@shao2-debian>

[-- Attachment #1: Type: text/plain, Size: 1217 bytes --]

On Tue, Sep 03, 2019 at 04:41:22PM +0800, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed a -23.7% regression of vm-scalability.median due to commit:
> 
> 
> commit: 8bb3c61bafa8c1cd222ada602bb94ff23119e738 ("vfs: Convert ramfs, shmem, tmpfs, devtmpfs, rootfs to use the new mount API")
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/viro/vfs.git work.mount
> 
> in testcase: vm-scalability
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 128G memory
> with following parameters:
> 
> 	runtime: 300s
> 	size: 16G
> 	test: shm-pread-rand
> 	cpufreq_governor: performance
> 	ucode: 0xb000036

That thing loses size=... option.  Both size= and nr_blocks= affect the
same thing (->max_blocks), but the parser keeps track of the options
it has seen and applying the parsed data to superblock checks only
whether nr_blocks= had been there.  IOW, size= gets parsed, but the
result goes nowhere.

I'm not sure whether it's better to fix the patch up or redo it from
scratch - it needs to be carved up anyway and it's highly non-transparent,
so I'm probably going to replace the damn thing entirely with something
that would be easier to follow.

  reply	other threads:[~2019-09-08 21:46 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03  8:41 [vfs] 8bb3c61baf: vm-scalability.median -23.7% regression kernel test robot
2019-09-03  8:41 ` kernel test robot
2019-09-08 21:46 ` Al Viro [this message]
2019-09-08 21:46   ` Al Viro
2019-09-08 23:47   ` Al Viro
2019-09-08 23:47     ` Al Viro
2019-09-09  3:10     ` Hugh Dickins
2019-09-09  3:10       ` Hugh Dickins
2019-09-09  3:56       ` Al Viro
2019-09-09  3:56         ` Al Viro
2019-09-10  6:27         ` Hugh Dickins
2019-09-10  6:27           ` Hugh Dickins
2019-09-11  3:05           ` Hugh Dickins
2019-09-11  3:05             ` Hugh Dickins

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