From: Steven Rostedt <rostedt@goodmis.org>
To: Tang Yizhou <yizhou.tang@shopee.com>
Cc: tj@kernel.org, jack@suse.cz, brauner@kernel.org,
willy@infradead.org, akpm@linux-foundation.org,
mhiramat@kernel.org, ast@kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] writeback: Let trace_balance_dirty_pages() take struct dtc as parameter
Date: Tue, 4 Mar 2025 10:39:57 -0500 [thread overview]
Message-ID: <20250304103957.08c79da0@gandalf.local.home> (raw)
In-Reply-To: <20250304110318.159567-2-yizhou.tang@shopee.com>
On Tue, 4 Mar 2025 19:03:16 +0800
Tang Yizhou <yizhou.tang@shopee.com> wrote:
> @@ -664,16 +660,16 @@ TRACE_EVENT(balance_dirty_pages,
> ),
>
> TP_fast_assign(
> - unsigned long freerun = (thresh + bg_thresh) / 2;
> + unsigned long freerun = (dtc->thresh + dtc->bg_thresh) / 2;
> strscpy_pad(__entry->bdi, bdi_dev_name(wb->bdi), 32);
>
> __entry->limit = global_wb_domain.dirty_limit;
> __entry->setpoint = (global_wb_domain.dirty_limit +
> freerun) / 2;
> - __entry->dirty = dirty;
> + __entry->dirty = dtc->dirty;
> __entry->bdi_setpoint = __entry->setpoint *
> - bdi_thresh / (thresh + 1);
> - __entry->bdi_dirty = bdi_dirty;
> + dtc->wb_thresh / (dtc->thresh + 1);
> + __entry->bdi_dirty = dtc->wb_dirty;
> __entry->dirty_ratelimit = KBps(dirty_ratelimit);
> __entry->task_ratelimit = KBps(task_ratelimit);
> __entry->dirtied = dirtied;
I don't know how much of a fast path these tracepoints are in, but instead
of doing the divisions above, why not just save the values in the ring
buffer, and do the divisions in the TP_printk() section, which is done when
the user reads it and not when the code is executing?
-- Steve
next prev parent reply other threads:[~2025-03-04 15:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-04 11:03 [PATCH v2 0/3] Fix calculations in trace_balance_dirty_pages() for cgwb Tang Yizhou
2025-03-04 11:03 ` [PATCH v2 1/3] writeback: Let trace_balance_dirty_pages() take struct dtc as parameter Tang Yizhou
2025-03-04 15:39 ` Steven Rostedt [this message]
2025-03-04 11:03 ` [PATCH v2 2/3] writeback: Rename variables in trace_balance_dirty_pages() Tang Yizhou
2025-03-04 11:03 ` [PATCH v2 3/3] writeback: Fix calculations in trace_balance_dirty_pages() for cgwb Tang Yizhou
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