linux-kernel - Kconfig help entry for CONFIG_PARAVIRT

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-next>] [day] [month] [year] [list]

Message-ID: <932951750.20131015234558@eikelenboom.it>
Date:	Tue, 15 Oct 2013 23:45:58 +0200
From:	Sander Eikelenboom <linux@...elenboom.it>
To:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
CC:	linux-kernel@...r.kernel.org
Subject: Kconfig help entry for CONFIG_PARAVIRT_SPINLOCK

Hi Raghavendra,

Since the ticketlock series have landed in this mergewindow (thanks :-) ) the
help accompanying the Kconfig entry doesn't seem to reflect the current state well.

- Wasn't the whole purpose of the ticketlock series to mitigate this 5% performance hit to something
  far less, so distro kernels could enable this for their normal kernels ?
  I don't have the exact performance figures though.

- Perhaps the suggestion to enable this for supported hypervisors (Xen and KVM ?) could be added ?

--
Sander


CONFIG_PARAVIRT_SPINLOCKS:

Paravirtualized spinlocks allow a pvops backend to replace the
spinlock implementation with something virtualization-friendly
(for example, block the virtual CPU rather than spinning).

Unfortunately the downside is an up to 5% performance hit on
native kernels, with various workloads.

If you are unsure how to answer this question, answer N.

Symbol: PARAVIRT_SPINLOCKS [=y]
Type  : boolean
Prompt: Paravirtualization layer for spinlocks
  Location:
    -> Processor type and features
      -> Linux guest support (HYPERVISOR_GUEST [=y])
        -> Enable paravirtualization code (PARAVIRT [=y])
  Defined at arch/x86/Kconfig:632
  Depends on: HYPERVISOR_GUEST [=y] && PARAVIRT [=y] && SMP [=y]
  Selects: UNINLINE_SPIN_UNLOCK [=y]


--
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/