From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f174.google.com (mail-lj1-f174.google.com [209.85.208.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67E821D0F63; Tue, 19 Nov 2024 18:07:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732039670; cv=none; b=IijXZ6sX82ArgihpZZOTE5/vCb8QUeACgPdQENldtf1QT+KzA46SE4pjFWZKxgzSDYhZqdlA0iXuzIpheTv7mowqlkAK5wl23xuA9+ehN0RzPSrZSKva3KhY14tMtrGViOHUlzmvnpGRnS82gucltkleq5enYMrNCbCs1NB89Wc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732039670; c=relaxed/simple; bh=oQF52UOBsgf58DOkdl1sz4LFstivHLwN3+CsZzhtXDg=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=SqO8crX/izYtRoJWeK+e0fgDPKNpzFjH4fo+JIPL1nu21VHvfJANkxt0HCGoOvsErOwQsLJIFEz0mzdvsuMYPcWEwQ+C8iG0NROmvveVyYt/fitkcVOO2KnAVqKE+uQFe/7bK8n5rvTeicPTyF6oNoyYLUGS2EQULEz5AOl1hao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=UaiEF/uh; arc=none smtp.client-ip=209.85.208.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UaiEF/uh" Received: by mail-lj1-f174.google.com with SMTP id 38308e7fff4ca-2fb56cb61baso36756431fa.1; Tue, 19 Nov 2024 10:07:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1732039666; x=1732644466; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=6q0Eekqr4PrHChR3kf477Bf+y3yz5ioREserDyGSgco=; b=UaiEF/uhfMicRKP+N4IqWJZy4lDp4tKtBDQ06P+zUE5AVIVZ8dE4SJPnF8MlEbT4zT rmVUFw/duwClvO22tL0kNaSxfpo7sb+ly40ZsMYSYh0Qz3H5DdECI0syNo8QE0MC5/in 9n6uqUXEFTsfFy/0s/9aZ2j/U4/Jwr81BjLFuqYGOIDQT3puh9ChorJNu07eFWaBBBIw t5/WsFQYb6/FvO4UQBmLprvd3nJRmOKr83Ba1IN8Qd716kFJNxP36bFyGmCZQoWDxtlE BO/sVC8GaZdXbXYC9/OCGNVohb9Y+qMdzbyovlQlZzgGhWepbJ492OyfoBIBkrX2NgE/ bdtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732039666; x=1732644466; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=6q0Eekqr4PrHChR3kf477Bf+y3yz5ioREserDyGSgco=; b=S2CfzlTBW6ML41OkYX2z+K71uieNDByWTAPeKjazC8TNbdMr6CJQ48IRRt81WuOISr CXPjxQpVGzGcBD31ddS6rhzvR3yALay72vdZJPhOiwbH7pXWeVq+XOX7DWf+c35K+IbT YxIl5DN/B4tZYBK5lkZ1cA8MUCBU5ABCJn+LCXeTvWjz8PgVWsu2e3jnVytnU5XTQJ7E +jr/35Gsoct9oq3I8RCQY/xN8zxJpsoPWKrpBPvdVGUqHYwXeSAaaC1NotRH7r2vHeDI 1/eMk9A7k5tm7sMJA/+OGsYRv9H8D4LjfzI68CNlyGG1UdzaLmquCxUohiEc25fmQ2el I07Q== X-Forwarded-Encrypted: i=1; AJvYcCVH/CGW7a71her8rkS0rnYd8yd2GQGG/Ydvp6XjbAWX0IdyRTj9qhbZTEnRPSpCsDKTrP9gNOsn+5NB@vger.kernel.org, AJvYcCVpiNJAuKkSa8b5pP9+sM28WWvvTcbtktUka0MZRZPAuTO/JBL7kRf64G9zkrT6gAK8EIBcS1W6dy8OiQ9Z@vger.kernel.org, AJvYcCXL5aXOg8GXIMNwRdYbB77z5RErzvmSFQtcac0O8UBcBNb2QP9PG10I+IiAUx7lFYG4idmkO2GFxqIzPbLm7A==@vger.kernel.org X-Gm-Message-State: AOJu0YzMEJDWN0a2i7b9CiruyT+cLAbEk03XPtKVMutfXax9Ue9PVB10 KEq7VwsQEwney/9d3nd6VmEUnM8DOIhnta8hvHXY9C+1+impsUbwQ5ZsB2gZWkY7QOGwgrVKpY7 sQ8/Tkz+xrycdpcuM1itOq2TEej0= X-Google-Smtp-Source: AGHT+IHdqoConUqClj8wLIM0mBnQdxHrbtF0Di+KOTfg36XQ9fCzKrtjZchTS75uFzJMILm9d1Yqc4hTdgQdLeKqdac= X-Received: by 2002:a2e:b88e:0:b0:2fb:59dc:735a with SMTP id 38308e7fff4ca-2ff607494aemr69833731fa.41.1732039666148; Tue, 19 Nov 2024 10:07:46 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241119094555.660666-1-mjguzik@gmail.com> <20241119175355.GB3484088@mit.edu> In-Reply-To: <20241119175355.GB3484088@mit.edu> From: Mateusz Guzik Date: Tue, 19 Nov 2024 19:07:33 +0100 Message-ID: Subject: Re: [PATCH v2 0/3] symlink length caching To: "Theodore Ts'o" Cc: brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, hughd@google.com, linux-ext4@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Nov 19, 2024 at 6:53=E2=80=AFPM Theodore Ts'o wrote= : > > On Tue, Nov 19, 2024 at 10:45:52AM +0100, Mateusz Guzik wrote: > > > > On my v1 Jan remarked 1.5% is not a particularly high win questioning > > whether doing this makes sense. I noted the value is only this small > > because of other slowdowns. > > Do you have a workload in mind which calls readlink() at sufficiently > high numbers such that this would be noticeable in > non-micro-benchmarks? What motiviated you to do this work? > I'm just messing about here. Given the triviality of the patch I'm not sure where the objection is coming from. I can point a finger at changes made by other people for supposed perf gains which are virtually guaranteed to be invisible in isolation, just like this one. Anyhow, I landed here from strlen -- the sucker is operating one byte at a time which I was looking to sort out, but then I noticed that one of the more commonly executing consumers does not even need to call it. --=20 Mateusz Guzik