linux-kernel - Re: [PATCH v1 0/7] DCE/DSE: Add Dead Syscalls Elimination support, part1

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Date:   Sat, 30 Sep 2023 17:31:32 +0800
From:   Yuan Tan <tanyuan@...ylab.org>
To:     falcon@...ylab.org
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux@...ssschuh.net, palmer@...osinc.com,
        paul.walmsley@...ive.com, paulburton@...nel.org,
        paulmck@...nel.org, tim.bird@...y.com, tsbogend@...ha.franken.de,
        w@....eu
Subject: Re: [PATCH v1 0/7] DCE/DSE: Add Dead Syscalls Elimination support, part1

I don't know why linux-kernel@...r.kernel.org reject my email send out by
thunderbird. So here I am resending this mail with git send-email.

Here is a test result about DEAD_CODE_DATA_ELIMINATION (DCE) and dead syscalls
elimination (DSE). It's based on config[1] and a simple hello.c initramfs.

In the DSE test, we set CONFIG_SYSCALLS_USED="sys_write sys_exit
sys_reboot," which is used by hello.c to simply print "Hello" then exit
and shut down qemu.

|                                    | syscall remain | vmlinux size     | vmlinux after strip |
| ---------------------------------- | -------------- | ---------------- | ------------------- |
| disable DCE                        | 236            | 2559632          | 1963400             |
| enable DCE                         | 208            | 2037384 (-20.4%) | 1485776 (-24.3%)    |
| enable DCE and DSE(SHE_GROUP)      | 3              | 1856640 (-27.6%) | 1354424 (-31.0%)    |
| enable DCE and DSE(SHE_LINK_ORDER) | 3              | 1856664 (-27.6%) | 1354424 (-31.0%)    |

It shows that dead syscalls elimination can save 7% of space based on DCE.

[1]: https://pastebin.com/KG4fd7aT