Re: [PATCH 6/6] x86: Allow disabling HW_BREAKPOINTS and PERF_EVENTS
From: Ingo Molnar
Date: Tue Oct 08 2013 - 02:59:49 EST
* Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>
> > text data bss dec hex filename
> > 13692640 1922416 1478656 17093712 104d450 obj/vmlinux
> > 12980092 1787544 1470464 16238100 f7c614 obj-noperf/vmlinux
[...]
> > Ok I trust you will do a better solution then to save the 700+k text.
> > Ball is in your court.
>
> Btw., could you send me your .config so I can investigate this?
Ok, you sent me your .config off-list - I won't re-post the full config,
but it can be reproduced by others fairly accurately by appending the
attached list of config symbols to a 'make defconfig' x86-64 .config and
running 'make oldconfig'.
So I test-built a config close to your config with both tracing and perf
on and off (note, I had OPROFILE and KVM in a module), and got the
following kernel sizes:
text data bss dec hex filename
====================================================================================
12081246 1279656 1003520 14364422 db2f06 vmlinux.perf-OFF.tracing-OFF
12979238 1785192 1150976 15915406 f2d98e vmlinux.perf-OFF.tracing-ON
12232758 1325424 1003520 14561702 de31a6 vmlinux.perf-ON.tracing-OFF
13223817 1877872 1150976 16252665 f7fef9 vmlinux.perf-ON.tracing-ON
Firstly, your 'perf increases vmlinux size by 700k' result does not seem
to reproduce, at all. [*]
[ Are you sure you made the measurement correctly? Please send me _both_
configs you used for the test, one with perf enabled, and the other one
with perf disabled, so I can double check it. I suppose you tested a
recent Linus kernel with your hardware-breakpoint patches applied. ]
Secondly and more importantly, visualized with relative sizes, in a
feature matrix, makes it clearer what's going on with vmlinux .text:
perf-OFF perf-ON
ftrace-OFF 0 +151k
ftrace-ON +897k +1142k
So basically ftrace is causing a big chunk of the instrumentation size
increase. With tons of tracers and lots of kernel subsystems built into
your .config that's a lot of nice instrumentation functionality and it's
thus also a natural end result IMO.
The base cost of perf is +151k - not small but a far cry from your claimed
+700k ...
In any case, on one hand I obviously welcome genuine kernel size
reductions, on the other hand what you did in these patches wasn't really
size reduction usable to too many people: all distros enable perf and
tracing and very few kernel developers are left who are still using
oprofile. You fought the symptom, not the reason.
So my NAK against your series stands. To sum up the technical reasons:
- you blaming +700k on perf alone is wrong, or at most a red herring
- your patches might break apps/ABI
- your patch-set unnecessarily complicates things, making the kernel
less maintainable
- details of your patch-set are broken as well, see the discussions
( There might be more reasons, this is just off the top of my head.
Any of these reasons would be enough to not apply your patches.)
You might want to concentrate your efforts from fighting perf
functionality towards decreasing per tracepoint overhead instead,
without hurting kernel functionality and maintainability.
Thanks,
Ingo
=================>
CONFIG_LOCALVERSION_AUTO=y
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_SYSFS_DEPRECATED=y
CONFIG_EXPERT=y
CONFIG_KALLSYMS_ALL=y
CONFIG_COMPAT_BRK=y
CONFIG_OPROFILE=y
CONFIG_OPROFILE_EVENT_MULTIPLEX=y
CONFIG_JUMP_LABEL=y
CONFIG_KPROBES_ON_FTRACE=y
CONFIG_USER_RETURN_NOTIFIER=y
CONFIG_MODULE_FORCE_LOAD=y
CONFIG_PREEMPT_NOTIFIERS=y
CONFIG_X86_MCE_INJECT=y
CONFIG_NUMA_EMU=y
CONFIG_MEMORY_ISOLATION=y
CONFIG_MMU_NOTIFIER=y
CONFIG_MEMORY_FAILURE=y
CONFIG_HWPOISON_INJECT=y
CONFIG_TRANSPARENT_HUGEPAGE=y
CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y
CONFIG_EFI_STUB=y
CONFIG_HZ_250=y
CONFIG_COMPAT_VDSO=y
CONFIG_PM_RUNTIME=y
CONFIG_ACPI_PROCFS_POWER=y
CONFIG_CPU_FREQ_STAT=y
CONFIG_CPU_FREQ_STAT_DETAILS=y
CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
CONFIG_CPU_FREQ_GOV_POWERSAVE=y
CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
CONFIG_X86_POWERNOW_K8=y
CONFIG_INTEL_IDLE=y
CONFIG_PCIEAER_INJECT=y
CONFIG_PCIE_PME=y
CONFIG_PCI_IOAPIC=y
CONFIG_IA32_AOUT=y
CONFIG_COMPAT_NETLINK_MESSAGES=y
CONFIG_INET_DIAG=y
CONFIG_INET_TCP_DIAG=y
CONFIG_INET_UDP_DIAG=y
CONFIG_BPF_JIT=y
CONFIG_WEXT_CORE=y
CONFIG_WEXT_PROC=y
CONFIG_CFG80211_WEXT=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_BLK_DEV_CRYPTOLOOP=y
CONFIG_BLK_DEV_RAM=y
CONFIG_SCSI_NETLINK=y
CONFIG_SCSI_SCAN_ASYNC=y
CONFIG_SCSI_FC_ATTRS=y
CONFIG_SCSI_LOWLEVEL=y
CONFIG_MEGARAID_SAS=y
CONFIG_SATA_NV=y
CONFIG_SATA_SIL=y
CONFIG_SATA_SVW=y
CONFIG_PATA_ATIIXP=y
CONFIG_PATA_PDC2027X=y
CONFIG_PATA_MPIIX=y
CONFIG_PATA_ACPI=y
CONFIG_ATA_GENERIC=y
CONFIG_DM_CRYPT=y
CONFIG_FIREWIRE=y
CONFIG_FIREWIRE_OHCI=y
CONFIG_TUN=y
CONFIG_MDIO=y
CONFIG_VORTEX=y
CONFIG_B44=y
CONFIG_B44_PCI_AUTOSELECT=y
CONFIG_B44_PCICORE_AUTOSELECT=y
CONFIG_B44_PCI=y
CONFIG_BNX2=y
CONFIG_TULIP=y
CONFIG_E1000E=y
CONFIG_IGB=y
CONFIG_IGB_HWMON=y
CONFIG_IXGB=y
CONFIG_IXGBE=y
CONFIG_IXGBE_HWMON=y
CONFIG_R8169=y
CONFIG_BROADCOM_PHY=y
CONFIG_USB_USBNET=y
CONFIG_USB_NET_AX8817X=y
CONFIG_USB_NET_AX88179_178A=y
CONFIG_USB_NET_CDC_NCM=y
CONFIG_USB_NET_MCS7830=y
CONFIG_USB_ALI_M5632=y
CONFIG_USB_AN2720=y
CONFIG_USB_BELKIN=y
CONFIG_USB_ARMLINUX=y
CONFIG_USB_EPSON2888=y
CONFIG_INPUT_MOUSEDEV_PSAUX=y
CONFIG_LEGACY_PTYS=y
CONFIG_SERIAL_KGDB_NMI=y
CONFIG_CONSOLE_POLL=y
CONFIG_HW_RANDOM_INTEL=y
CONFIG_HW_RANDOM_AMD=y
CONFIG_RAW_DRIVER=y
CONFIG_HPET_MMAP=y
CONFIG_SSB=y
CONFIG_SSB_SPROM=y
CONFIG_SSB_PCIHOST_POSSIBLE=y
CONFIG_SSB_PCIHOST=y
CONFIG_SSB_DRIVER_PCICORE_POSSIBLE=y
CONFIG_SSB_DRIVER_PCICORE=y
CONFIG_DRM_TTM=y
CONFIG_DRM_RADEON=y
CONFIG_FB_DDC=y
CONFIG_FB_BACKLIGHT=y
CONFIG_FB_RADEON=y
CONFIG_FB_RADEON_I2C=y
CONFIG_FB_RADEON_BACKLIGHT=y
CONFIG_SOUND_PRIME=y
CONFIG_HID_BATTERY_STRENGTH=y
CONFIG_HID_DRAGONRISE=y
CONFIG_HID_KYE=y
CONFIG_HID_TWINHAN=y
CONFIG_HID_ORTEK=y
CONFIG_HID_GREENASIA=y
CONFIG_HID_SMARTJOYPLUS=y
CONFIG_HID_THRUSTMASTER=y
CONFIG_HID_ZEROPLUS=y
CONFIG_USB_STORAGE_REALTEK=y
CONFIG_REALTEK_AUTOPM=y
CONFIG_USB_STORAGE_DATAFAB=y
CONFIG_USB_STORAGE_FREECOM=y
CONFIG_USB_STORAGE_ISD200=y
CONFIG_USB_STORAGE_USBAT=y
CONFIG_USB_STORAGE_SDDR09=y
CONFIG_USB_STORAGE_SDDR55=y
CONFIG_USB_STORAGE_JUMPSHOT=y
CONFIG_USB_STORAGE_ALAUDA=y
CONFIG_USB_STORAGE_ONETOUCH=y
CONFIG_USB_STORAGE_KARMA=y
CONFIG_USB_STORAGE_CYPRESS_ATACB=y
CONFIG_USB_STORAGE_ENE_UB6250=y
CONFIG_EFI_VARS_PSTORE=y
CONFIG_REISERFS_FS=y
CONFIG_REISERFS_FS_XATTR=y
CONFIG_REISERFS_FS_POSIX_ACL=y
CONFIG_EXPORTFS=y
CONFIG_UDF_FS=y
CONFIG_UDF_NLS=y
CONFIG_PSTORE=y
CONFIG_PSTORE_CONSOLE=y
CONFIG_PSTORE_FTRACE=y
CONFIG_PSTORE_RAM=y
CONFIG_NFSD=y
CONFIG_NFSD_V3=y
CONFIG_CIFS=y
CONFIG_CIFS_DEBUG=y
CONFIG_NLS_ISO8859_15=y
CONFIG_DYNAMIC_DEBUG=y
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_INFO_REDUCED=y
CONFIG_ENABLE_WARN_DEPRECATED=y
CONFIG_READABLE_ASM=y
CONFIG_UNUSED_SYMBOLS=y
CONFIG_DETECT_HUNG_TASK=y
CONFIG_SCHED_DEBUG=y
CONFIG_LATENCYTOP=y
CONFIG_TRACER_MAX_TRACE=y
CONFIG_RING_BUFFER_ALLOW_SWAP=y
CONFIG_FUNCTION_TRACER=y
CONFIG_FUNCTION_GRAPH_TRACER=y
CONFIG_SCHED_TRACER=y
CONFIG_FTRACE_SYSCALLS=y
CONFIG_TRACER_SNAPSHOT=y
CONFIG_DYNAMIC_FTRACE=y
CONFIG_DYNAMIC_FTRACE_WITH_REGS=y
CONFIG_FTRACE_MCOUNT_RECORD=y
CONFIG_FIREWIRE_OHCI_REMOTE_DMA=y
CONFIG_KGDB=y
CONFIG_KGDB_SERIAL_CONSOLE=y
CONFIG_KGDB_KDB=y
CONFIG_KDB_KEYBOARD=y
CONFIG_X86_PTDUMP=y
CONFIG_IO_DELAY_0XED=y
CONFIG_DEFAULT_SECURITY_DAC=y
CONFIG_CRYPTO_RNG=y
CONFIG_CRYPTO_GF128MUL=y
CONFIG_CRYPTO_NULL=y
CONFIG_CRYPTO_CRYPTD=y
CONFIG_CRYPTO_CCM=y
CONFIG_CRYPTO_GCM=y
CONFIG_CRYPTO_SEQIV=y
CONFIG_CRYPTO_CTR=y
CONFIG_CRYPTO_CTS=y
CONFIG_CRYPTO_ECB=y
CONFIG_CRYPTO_LRW=y
CONFIG_CRYPTO_PCBC=y
CONFIG_CRYPTO_CMAC=y
CONFIG_CRYPTO_CRCT10DIF=y
CONFIG_CRYPTO_GHASH=y
CONFIG_CRYPTO_MD4=y
CONFIG_CRYPTO_SHA256=y
CONFIG_CRYPTO_SHA512=y
CONFIG_CRYPTO_AES_X86_64=y
CONFIG_HAVE_KVM_IRQCHIP=y
CONFIG_HAVE_KVM_IRQ_ROUTING=y
CONFIG_HAVE_KVM_EVENTFD=y
CONFIG_KVM_APIC_ARCHITECTURE=y
CONFIG_KVM_MMIO=y
CONFIG_KVM_ASYNC_PF=y
CONFIG_HAVE_KVM_MSI=y
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT=y
CONFIG_KVM=y
CONFIG_KVM_INTEL=y
CONFIG_CRC_T10DIF=y
CONFIG_CRC_ITU_T=y
CONFIG_LIBCRC32C=y
CONFIG_ZLIB_DEFLATE=y
CONFIG_XZ_DEC_POWERPC=y
CONFIG_XZ_DEC_IA64=y
CONFIG_XZ_DEC_ARM=y
CONFIG_XZ_DEC_ARMTHUMB=y
CONFIG_XZ_DEC_SPARC=y
CONFIG_REED_SOLOMON=y
CONFIG_REED_SOLOMON_ENC8=y
CONFIG_REED_SOLOMON_DEC8=y
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