From owner-freebsd-stable@freebsd.org  Fri Oct 21 11:51:34 2016
Return-Path: <owner-freebsd-stable@freebsd.org>
Delivered-To: freebsd-stable@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 47602C1B122
 for <freebsd-stable@mailman.ysv.freebsd.org>;
 Fri, 21 Oct 2016 11:51:34 +0000 (UTC)
 (envelope-from emz@norma.perm.ru)
Received: from elf.hq.norma.perm.ru (mail.norma.perm.ru [IPv6:2a00:7540:1::5])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256
 bits)) (Client CN "mail.norma.perm.ru",
 Issuer "Vivat-Trade UNIX Root CA" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id B5A0C3A7
 for <freebsd-stable@freebsd.org>; Fri, 21 Oct 2016 11:51:33 +0000 (UTC)
 (envelope-from emz@norma.perm.ru)
Received: from [IPv6:2a02:2698:27:b4d9:28e5:c182:e05b:6a1e]
 ([IPv6:2a02:2698:27:b4d9:28e5:c182:e05b:6a1e]) (authenticated bits=0)
 by elf.hq.norma.perm.ru (8.15.2/8.15.2) with ESMTPSA id u9LBpTPY098847
 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO)
 for <freebsd-stable@freebsd.org>; Fri, 21 Oct 2016 16:51:30 +0500 (YEKT)
 (envelope-from emz@norma.perm.ru)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=norma.perm.ru; s=key;
 t=1477050690; bh=C27w+cY1oxEbOzuIxxQxcVFq9rqXAL4f9YE7mjYRbYQ=;
 h=Subject:To:References:From:Date:In-Reply-To;
 b=txOU6bkhXjurdBpfYYRtuWnZ8Hpox7H7SR4yYF29rue2TylgiOAjeMEu+r4A5gPW4
 JwIQ8dbbt36L1QThuo8CfY8SHSFguiBFgqK8fWqbjrevEdZefp243ydUyZkYrHuGQI
 D8SY6Vuc9lHhOz48Xb+fNu+RrQGRI48WhlakOCcQ=
Subject: Re: zfs, a directory that used to hold lot of files and listing pause
To: freebsd-stable@freebsd.org
References: <4d9269af-ed64-bb73-eb7f-98a3f5ffd5a2@norma.perm.ru>
 <40fa9fd6-15aa-d8f7-b958-8783e763e6bc@multiplay.co.uk>
 <577ab7b2-46c1-5cf0-b6ad-50895978d957@norma.perm.ru>
 <38a84fce-fd97-a6a1-5820-89e578d76f0b@multiplay.co.uk>
 <91f34889-7f4f-661d-c88f-8034402c39cd@norma.perm.ru>
 <19a45e94-65e6-53a9-202d-c048055460d1@multiplay.co.uk>
 <20161021102051.GH57876@zxy.spb.ru>
From: "Eugene M. Zheganin" <emz@norma.perm.ru>
Message-ID: <499a3693-d8ea-8b47-138c-77876077967c@norma.perm.ru>
Date: Fri, 21 Oct 2016 16:51:36 +0500
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <20161021102051.GH57876@zxy.spb.ru>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-stable>, 
 <mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable/>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 21 Oct 2016 11:51:34 -0000

Hi.

On 21.10.2016 15:20, Slawa Olhovchenkov wrote:
>
> ZFS prefetch affect performance dpeneds of workload (independed of RAM
> size): for some workloads wins, for some workloads lose (for my
> workload prefetch is lose and manualy disabled with 128GB RAM).
>
> Anyway, this system have only 24MB in ARC by 2.3GB free, this is may
> be too low for this workload.
You mean - "for getting a list of a directory with 20 subdirectories" ? 
Why then does only this directory have this issue with pause, not 
/usr/ports/..., which has more directories in it ?

(and yes, /usr/ports/www isn't empty and holds 2410 entities)

/usr/bin/time -h ls -1 /usr/ports/www
[...]
0.14s real              0.00s user              0.00s sys

Thanks.
Eugene.