linux-kernel - Re: [PATCH] tmpfs: use ida to get inode number

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Message-ID: <20191123023325.GY20752@bombadil.infradead.org>
Date:   Fri, 22 Nov 2019 18:33:25 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     "zhengbin (A)" <zhengbin13@...wei.com>
Cc:     Hugh Dickins <hughd@...gle.com>, viro@...iv.linux.org.uk,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        houtao1@...wei.com, yi.zhang@...wei.com,
        "J. R. Okajima" <hooanon05g@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH] tmpfs: use ida to get inode number

On Sat, Nov 23, 2019 at 10:16:39AM +0800, zhengbin (A) wrote:
> By the way, percpu IDA is for reducing performance impact? This patch has 2.16%
> performance degradation(Use perf to get the cost of ida_alloc_range)

2.16% degradation in your tests ... I bet Eric didn't make it so complex
for only 2% performance impact.  Unfortunately, he didn't give any
numbers in his patch submission, but it's going to be a bigger problem
on multi-socket machines than on a laptop.

Eric, any memories from 2010?  Commit
f991bd2e14210fb93d722cb23e54991de20e8a3d if it helps.