From: Chao Yu <yuchao0@huawei.com>
To: "Theodore Y. Ts'o" <tytso@mit.edu>, Gao Xiang <gaoxiang25@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
Jaegeuk Kim <jaegeuk@kernel.org>
Subject: Re: [f2fs-dev] [PATCH] f2fs: bio_alloc should never fail
Date: Thu, 31 Oct 2019 10:03:21 +0800 [thread overview]
Message-ID: <61fc6d47-1cb3-4646-d155-444cff0b5b3e@huawei.com> (raw)
In-Reply-To: <20191030151444.GC16197@mit.edu>
On 2019/10/30 23:14, Theodore Y. Ts'o wrote:
> On Wed, Oct 30, 2019 at 06:43:45PM +0800, Gao Xiang wrote:
>>> You're right, in low memory scenario, allocation with bioset will be faster, as
>>> you mentioned offline, maybe we can add/use a priviate bioset like btrfs did
>>> rather than using global one, however, we'd better check how deadlock happen
>>> with a bioset mempool first ...
>>
>> Okay, hope to get hints from Jaegeuk and redo this patch then...
>
> It's not at all clear to me that using a private bioset is a good idea
> for f2fs. That just means you're allocating a separate chunk of
> memory just for f2fs, as opposed to using the global pool. That's an
> additional chunk of non-swapable kernel memory that's not going to be
> available, in *addition* to the global mempool.
>
> Also, who else would you be contending for space with the global
> mempool? It's not like an mobile handset is going to have other users
> of the global bio mempool.
>
> On a low-end mobile handset, memory is at a premium, so wasting memory
> to no good effect isn't going to be a great idea.
You're right, it looks that the purpose that btrfs added private bioset is to
avoid abusing bio internal fields (via commit 9be3395bcd4a), f2fs has no such
reason to do that now.
Thanks,
>
> Regards,
>
> - Ted
> .
>
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prev parent reply other threads:[~2019-10-31 2:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 3:55 [f2fs-dev] [PATCH] f2fs: bio_alloc should never fail Gao Xiang
2019-10-30 8:56 ` Chao Yu
2019-10-30 9:15 ` Gao Xiang
2019-10-30 9:27 ` Chao Yu
2019-10-30 10:43 ` Gao Xiang
2019-10-30 15:14 ` Theodore Y. Ts'o
2019-10-30 15:50 ` Gao Xiang via Linux-f2fs-devel
2019-10-30 16:22 ` Theodore Y. Ts'o
2019-10-30 16:33 ` Jaegeuk Kim
2019-10-30 16:52 ` Gao Xiang via Linux-f2fs-devel
2019-10-31 6:55 ` Chao Yu
2019-10-31 2:03 ` Chao Yu [this message]
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