linux-kernel - Re: [PATCH v2] uprobes: Improve the usage of xol slots for better scalability

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Message-ID: <20241001142935.GC23907@redhat.com>
Date: Tue, 1 Oct 2024 16:29:35 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Liao Chang <liaochang1@...wei.com>
Cc: ak@...ux.intel.com, mhiramat@...nel.org, andrii@...nel.org,
	peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
	namhyung@...nel.org, mark.rutland@....com,
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	irogers@...gle.com, adrian.hunter@...el.com,
	kan.liang@...ux.intel.com, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v2] uprobes: Improve the usage of xol slots for better
 scalability

On 09/27, Liao Chang wrote:
>
> The uprobe handler allocates xol slot from xol_area and quickly release
> it in the single-step handler. The atomic operations on the xol bitmap
> and slot_count lead to expensive cache line bouncing between multiple
> CPUs.

Liao, could you please check if this series

	[PATCH 0/2] uprobes: kill xol_area->slot_count
	https://lore.kernel.org/all/20241001142416.GA13599@redhat.com/

makes any difference performance-wise in your testing?

Oleg.