linux-kernel - Re: Poor performance on cp on kernel 2.6.27.7-9-xen (openSUSE 11.1)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID:  <498A430E.1040809@gmail.com>
Date:	Wed, 04 Feb 2009 19:38:22 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject:  Re: Poor performance on cp on kernel 2.6.27.7-9-xen (openSUSE 11.1)

Michael Monnerie wrote:
> And one last thing:
> rsync -aPv /disk1/bigfile /disk2/xxx
> That copies at max. 50MB/s, because 2 rsync tasks are started each 
> taking 50% of 1 CPU - why doesn't the kernel switch the 2nd task to 
> another CPU? There are 8 cpus in that system - 7 of them idle.

Usually in such cases it's because the tasks are piping data to each 
other in such a way that they can't both run at the same time. In this 
situation there is no point in moving one to another CPU because they're 
not executing concurrently anyway.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/