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From: Yanfei Xu <yanfei.xu@windriver.com>
To: daniel@iogearbox.net, ast@kernel.org, zlim.lnx@gmail.com,
	catalin.marinas@arm.com, will@kernel.org, andrii@kernel.org,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	john.fastabend@gmail.com, kpsingh@kernel.org
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 0/1] bpf: avoid unnecessary IPI in bpf_flush_icache
Date: Tue,  1 Jun 2021 23:06:24 +0800	[thread overview]
Message-ID: <20210601150625.37419-1-yanfei.xu@windriver.com> (raw)

Hi,

When looking at the IPI counts in /proc/interrupts, there are always 
IPI1 happened on isolated cpus, even if the cpus had been idle with 
nohz. However, we should bother these cpus as less as possible.

The IPI1 were raised by flush_icache_range in bpf_int_jit_compile(). 
Futher, the calling of it was introduced in 3b8c9f1cdfc5("arm64: 
IPI each CPU after invalidating the I-cache for kernel mappings"), 
then I found the bpf case seems no need this operation. But I'm not 
sure, and still learning the JIT codes meanwhile. If I am wrong, 
please fix me, many thanks!

Yanfei Xu (1):
  bpf: avoid unnecessary IPI in bpf_flush_icache

 arch/arm64/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.27.0


WARNING: multiple messages have this Message-ID (diff)
From: Yanfei Xu <yanfei.xu@windriver.com>
To: daniel@iogearbox.net, ast@kernel.org, zlim.lnx@gmail.com,
	catalin.marinas@arm.com, will@kernel.org, andrii@kernel.org,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	john.fastabend@gmail.com, kpsingh@kernel.org
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 0/1] bpf: avoid unnecessary IPI in bpf_flush_icache
Date: Tue,  1 Jun 2021 23:06:24 +0800	[thread overview]
Message-ID: <20210601150625.37419-1-yanfei.xu@windriver.com> (raw)

Hi,

When looking at the IPI counts in /proc/interrupts, there are always 
IPI1 happened on isolated cpus, even if the cpus had been idle with 
nohz. However, we should bother these cpus as less as possible.

The IPI1 were raised by flush_icache_range in bpf_int_jit_compile(). 
Futher, the calling of it was introduced in 3b8c9f1cdfc5("arm64: 
IPI each CPU after invalidating the I-cache for kernel mappings"), 
then I found the bpf case seems no need this operation. But I'm not 
sure, and still learning the JIT codes meanwhile. If I am wrong, 
please fix me, many thanks!

Yanfei Xu (1):
  bpf: avoid unnecessary IPI in bpf_flush_icache

 arch/arm64/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.27.0


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             reply	other threads:[~2021-06-01 15:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01 15:06 Yanfei Xu [this message]
2021-06-01 15:06 ` [PATCH 0/1] bpf: avoid unnecessary IPI in bpf_flush_icache Yanfei Xu
2021-06-01 15:06 ` [PATCH 1/1] " Yanfei Xu
2021-06-01 15:06   ` Yanfei Xu
2021-06-01 17:20   ` Daniel Borkmann
2021-06-01 17:20     ` Daniel Borkmann
2021-06-01 17:41     ` Will Deacon
2021-06-01 17:41       ` Will Deacon
2021-06-02 11:26       ` Xu, Yanfei
2021-06-02 11:26         ` Xu, Yanfei
2021-06-02 17:26         ` Will Deacon
2021-06-02 17:26           ` Will Deacon
2021-06-03 10:29           ` Xu, Yanfei
2021-06-03 10:29             ` Xu, Yanfei

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