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Srinivasa D S ef53d9c5e4 kprobes: improve kretprobe scalability with hashed locking ... Currently list of kretprobe instances are stored in kretprobe object (as used_instances,free_instances) and in kretprobe hash table. We have one global kretprobe lock to serialise the access to these lists. This causes only one kretprobe handler to execute at a time. Hence affects system performance, particularly on SMP systems and when return probe is set on lot of functions (like on all systemcalls). Solution proposed here gives fine-grain locks that performs better on SMP system compared to present kretprobe implementation. Solution: 1) Instead of having one global lock to protect kretprobe instances present in kretprobe object and kretprobe hash table. We will have two locks, one lock for protecting kretprobe hash table and another lock for kretporbe object. 2) We hold lock present in kretprobe object while we modify kretprobe instance in kretprobe object and we hold per-hash-list lock while modifying kretprobe instances present in that hash list. To prevent deadlock, we never grab a per-hash-list lock while holding a kretprobe lock. 3) We can remove used_instances from struct kretprobe, as we can track used instances of kretprobe instances using kretprobe hash table. Time duration for kernel compilation ("make -j 8") on a 8-way ppc64 system with return probes set on all systemcalls looks like this. cacheline non-cacheline Un-patched kernel aligned patch aligned patch =============================================================================== real 9m46.784s 9m54.412s 10m2.450s user 40m5.715s 40m7.142s 40m4.273s sys 2m57.754s 2m58.583s 3m17.430s =========================================================== Time duration for kernel compilation ("make -j 8) on the same system, when kernel is not probed. ========================= real 9m26.389s user 40m8.775s sys 2m7.283s ========================= Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com> Signed-off-by: Jim Keniston <jkenisto@us.ibm.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Masami Hiramatsu <mhiramat@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		17 years ago
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configs	[IA64] move defconfig to arch/ia64/configs/	17 years ago
dig	…
hp	simserial: Fix up for ldisc changes	17 years ago
ia32	flag parameters: pipe	17 years ago
kernel	kprobes: improve kretprobe scalability with hashed locking	17 years ago
kvm	KVM: MMU: nuke shadowed pgtable pages and ptes on memslot destruction	17 years ago
lib	…
mm	bootmem: replace node_boot_start in struct bootmem_data	17 years ago
oprofile	…
pci	PCI: ia64: use generic pci_enable_resources()	17 years ago
scripts	…
sn	Merge branch 'generic-ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	17 years ago
uv	[IA64] Fix CONFIG_IA64_SGI_UV build error	17 years ago
Kconfig	[IA64] Remove experimental status of kdump	17 years ago
Kconfig.debug	…
Makefile	Pull pvops into release branch	17 years ago
install.sh	…
module.lds	…