On Fri, May 27, 2022 at 07:09:59PM +0800, Zhang Yuchen wrote: > Add /proc/syscalls to display percpu syscall count. > > We need a less resource-intensive way to count syscall per cpu > for system problem location. > > There is a similar utility syscount in the BCC project, but syscount > has a high performance cost. > > The following is a comparison on the same machine, using UnixBench > System Call Overhead: > > ┏━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┳━━━━━━━━┓ > ┃ Change ┃ Unixbench Score ┃ Loss ┃ > ┡━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━╇━━━━━━━━┩ > │ no change │ 1072.6 │ --- │ > │ syscall count │ 982.5 │ 8.40% │ > │ bpf syscount │ 614.2 │ 42.74% │ > └───────────────┴─────────────────┴────────┘ > > UnixBench System Call Use sys_gettid to test, this system call only reads > one variable, so the performance penalty seems large. When tested with > fork, the test scores were almost the same. > > So the conclusion is that it does not have a significant impact on system > call performance. > > This function depends on CONFIG_FTRACE_SYSCALLS because the system call > number is stored in syscall_metadata. Death by a thousand cuts. 99% of people won't ever use this. NAK
