config UBIFS_FS tristate "UBIFS file system support" select CRC16 select CRC32 select CRYPTO if UBIFS_FS_ADVANCED_COMPR select CRYPTO if UBIFS_FS_LZO select CRYPTO if UBIFS_FS_ZLIB select CRYPTO_LZO if UBIFS_FS_LZO select CRYPTO_DEFLATE if UBIFS_FS_ZLIB depends on MTD_UBI help UBIFS is a file system for flash devices which works on top of UBI. config UBIFS_FS_ADVANCED_COMPR bool "Advanced compression options" depends on UBIFS_FS help This option allows to explicitly choose which compressions, if any, are enabled in UBIFS. Removing compressors means inability to read existing file systems. If unsure, say 'N'. config UBIFS_FS_LZO bool "LZO compression support" if UBIFS_FS_ADVANCED_COMPR depends on UBIFS_FS default y help LZO compressor is generally faster than zlib but compresses worse. Say 'Y' if unsure. config UBIFS_FS_ZLIB bool "ZLIB compression support" if UBIFS_FS_ADVANCED_COMPR depends on UBIFS_FS default y help Zlib compresses better than LZO but it is slower. Say 'Y' if unsure. config UBIFS_ATIME_SUPPORT bool "Access time support" if UBIFS_FS depends on UBIFS_FS default n help Originally UBIFS did not support atime, because it looked like a bad idea due increased flash wear. This option adds atime support and it is disabled by default to preserve the old behavior. If you enable this option, UBIFS starts updating atime, which means that file-system read operations will cause writes (inode atime updates). This may affect file-system performance and increase flash device wear, so be careful. How often atime is updated depends on the selected strategy: strictatime is the "heavy", relatime is "lighter", etc. If unsure, say 'N' config UBIFS_FS_ENCRYPTION bool "UBIFS Encryption" depends on UBIFS_FS && BLOCK select FS_ENCRYPTION default n help Enable encryption of UBIFS files and directories. This feature is similar to ecryptfs, but it is more memory efficient since it avoids caching the encrypted and decrypted pages in the page cache. a252c129225a899'>commitdiff
path: root/Documentation/acpi/method-tracing.txt
diff options
context:
space:
mode:
authorWanpeng Li <wanpeng.li@hotmail.com>2016-09-02 14:38:23 +0800
committerThomas Gleixner <tglx@linutronix.de>2016-09-02 10:25:40 +0200
commit08d072599234c959b0b82b63fa252c129225a899 (patch)
tree7e39e250570300bc66e42d922fa80327aaf1e573 /Documentation/acpi/method-tracing.txt
parent98744b408c757901df57fa50cbd5826245dc3a1f (diff)
tick/nohz: Fix softlockup on scheduler stalls in kvm guest
tick_nohz_start_idle() is prevented to be called if the idle tick can't be stopped since commit 1f3b0f8243cb934 ("tick/nohz: Optimize nohz idle enter"). As a result, after suspend/resume the host machine, full dynticks kvm guest will softlockup: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [swapper/0:0] Call Trace: default_idle+0x31/0x1a0 arch_cpu_idle+0xf/0x20 default_idle_call+0x2a/0x50 cpu_startup_entry+0x39b/0x4d0 rest_init+0x138/0x140 ? rest_init+0x5/0x140 start_kernel+0x4c1/0x4ce ? set_init_arg+0x55/0x55 ? early_idt_handler_array+0x120/0x120 x86_64_start_reservations+0x24/0x26 x86_64_start_kernel+0x142/0x14f In addition, cat /proc/stat | grep cpu in guest or host: cpu 398 16 5049 15754 5490 0 1 46 0 0 cpu0 206 5 450 0 0 0 1 14 0 0 cpu1 81 0 3937 3149 1514 0 0 9 0 0 cpu2 45 6 332 6052 2243 0 0 11 0 0 cpu3 65 2 328 6552 1732 0 0 11 0 0 The idle and iowait states are weird 0 for cpu0(housekeeping). The bug is present in both guest and host kernels, and they both have cpu0's idle and iowait states issue, however, host kernel's suspend/resume path etc will touch watchdog to avoid the softlockup. - The watchdog will not be touched in tick_nohz_stop_idle path (need be touched since the scheduler stall is expected) if idle_active flags are not detected. - The idle and iowait states will not be accounted when exit idle loop (resched or interrupt) if idle start time and idle_active flags are not set. This patch fixes it by reverting commit 1f3b0f8243cb934 since can't stop idle tick doesn't mean can't be idle. Fixes: 1f3b0f8243cb934 ("tick/nohz: Optimize nohz idle enter") Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Sanjeev Yadav<sanjeev.yadav@spreadtrum.com> Cc: Gaurav Jindal<gaurav.jindal@spreadtrum.com> Cc: stable@vger.kernel.org Cc: kvm@vger.kernel.org Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Link: http://lkml.kernel.org/r/1472798303-4154-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/acpi/method-tracing.txt')