From: Al Viro <viro@zeniv.linux.org.uk>
To: Matthew Wilcox <willy@infradead.org>
Cc: zhengbin <zhengbin13@huawei.com>,
hughd@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, houtao1@huawei.com,
yi.zhang@huawei.com
Subject: Re: [PATCH] tmpfs: use ida to get inode number
Date: Thu, 21 Nov 2019 04:31:27 +0000 [thread overview]
Message-ID: <20191121043127.GA26530@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20191120154552.GS20752@bombadil.infradead.org>
On Wed, Nov 20, 2019 at 07:45:52AM -0800, Matthew Wilcox wrote:
> On Wed, Nov 20, 2019 at 10:23:18PM +0800, zhengbin wrote:
> > I have tried to change last_ino type to unsigned long, while this was
> > rejected, see details on https://patchwork.kernel.org/patch/11023915.
>
> Did you end up trying sbitmap?
>
> What I think is fundamentally wrong with this patch is that you've found a
> problem in get_next_ino() and decided to use a different scheme for this
> one filesystem, leaving every other filesystem which uses get_next_ino()
> facing the same problem.
>
> That could be acceptable if you explained why tmpfs is fundamentally
> different from all the other filesystems that use get_next_ino(), but
> you haven't (and I don't think there is such a difference. eg pipes,
> autofs and ipc mqueue could all have the same problem.
If you think that anyone is willing to pay one hell of a price on each
pipe(2)... Note that get_next_ino() is pretty careful about staying
within per-cpu stuff most of the time; it hits any cross-CPU traffic
only in 1/1024th of calls. This, AFAICS, dirties shared cachelines
on each call. And there's a plenty of pipe-heavy workloads, for obvious
reasons.
prev parent reply other threads:[~2019-11-21 4:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-20 14:23 [PATCH] tmpfs: use ida to get inode number zhengbin
2019-11-20 15:45 ` Matthew Wilcox
2019-11-21 2:36 ` zhengbin (A)
2019-11-21 4:52 ` Hugh Dickins
2019-11-21 6:45 ` zhengbin (A)
2019-11-21 19:53 ` Hugh Dickins
2019-11-22 1:23 ` zhengbin (A)
2019-11-22 22:13 ` Matthew Wilcox
2019-11-23 2:16 ` zhengbin (A)
2019-11-23 2:33 ` Matthew Wilcox
2019-11-23 4:54 ` Al Viro
2019-12-01 8:44 ` zhengbin (A)
2019-11-21 11:40 ` J. R. Okajima
2019-11-21 20:07 ` Hugh Dickins
2019-11-21 4:31 ` Al Viro [this message]
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