From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Niklas Cassel <cassel@kernel.org>
Cc: "Krzysztof Wilczyński" <kw@linux.com>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Kuppuswamy Sathyanarayanan"
<sathyanarayanan.kuppuswamy@linux.intel.com>,
"Damien Le Moal" <dlemoal@kernel.org>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH v4] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests
Date: Sat, 4 May 2024 20:04:51 +0530 [thread overview]
Message-ID: <20240504143451.GA4315@thinkpad> (raw)
In-Reply-To: <20240322164139.678228-1-cassel@kernel.org>
On Fri, Mar 22, 2024 at 05:41:38PM +0100, Niklas Cassel wrote:
> The current code uses writel()/readl(), which has an implicit memory
> barrier for every single readl()/writel().
>
> Additionally, reading 4 bytes at a time over the PCI bus is not really
> optimal, considering that this code is running in an ioctl handler.
>
> Use memcpy_toio()/memcpy_fromio() for BAR tests.
>
> Before patch with a 4MB BAR:
> $ time /usr/bin/pcitest -b 1
> BAR1: OKAY
> real 0m 1.56s
>
> After patch with a 4MB BAR:
> $ time /usr/bin/pcitest -b 1
> BAR1: OKAY
> real 0m 0.54s
>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
- Mani
> ---
> Changes since v3:
> -Use scope-based resource management __free attribute from cleanup.h to
> avoid overly verbose gotos and labels for error handling.
> -Added a comment related to why we allocate a buffer of max 1MB.
> (kmalloc() default upper limit is usually 4 MB on ARM and x86.)
>
> drivers/misc/pci_endpoint_test.c | 54 +++++++++++++++++++++++++-------
> 1 file changed, 42 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> index 705029ad8eb5..bf64d3aff7d8 100644
> --- a/drivers/misc/pci_endpoint_test.c
> +++ b/drivers/misc/pci_endpoint_test.c
> @@ -7,6 +7,7 @@
> */
>
> #include <linux/crc32.h>
> +#include <linux/cleanup.h>
> #include <linux/delay.h>
> #include <linux/fs.h>
> #include <linux/io.h>
> @@ -272,31 +273,60 @@ static const u32 bar_test_pattern[] = {
> 0xA5A5A5A5,
> };
>
> +static int pci_endpoint_test_bar_memcmp(struct pci_endpoint_test *test,
> + enum pci_barno barno, int offset,
> + void *write_buf, void *read_buf,
> + int size)
> +{
> + memset(write_buf, bar_test_pattern[barno], size);
> + memcpy_toio(test->bar[barno] + offset, write_buf, size);
> +
> + memcpy_fromio(read_buf, test->bar[barno] + offset, size);
> +
> + return memcmp(write_buf, read_buf, size);
> +}
> +
> static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
> enum pci_barno barno)
> {
> - int j;
> - u32 val;
> - int size;
> + int j, bar_size, buf_size, iters, remain;
> + void *write_buf __free(kfree) = NULL;
> + void *read_buf __free(kfree) = NULL;
> struct pci_dev *pdev = test->pdev;
>
> if (!test->bar[barno])
> return false;
>
> - size = pci_resource_len(pdev, barno);
> + bar_size = pci_resource_len(pdev, barno);
>
> if (barno == test->test_reg_bar)
> - size = 0x4;
> + bar_size = 0x4;
>
> - for (j = 0; j < size; j += 4)
> - pci_endpoint_test_bar_writel(test, barno, j,
> - bar_test_pattern[barno]);
> + /*
> + * Allocate a buffer of max size 1MB, and reuse that buffer while
> + * iterating over the whole BAR size (which might be much larger).
> + */
> + buf_size = min(SZ_1M, bar_size);
>
> - for (j = 0; j < size; j += 4) {
> - val = pci_endpoint_test_bar_readl(test, barno, j);
> - if (val != bar_test_pattern[barno])
> + write_buf = kmalloc(buf_size, GFP_KERNEL);
> + if (!write_buf)
> + return false;
> +
> + read_buf = kmalloc(buf_size, GFP_KERNEL);
> + if (!read_buf)
> + return false;
> +
> + iters = bar_size / buf_size;
> + for (j = 0; j < iters; j++)
> + if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * j,
> + write_buf, read_buf, buf_size))
> + return false;
> +
> + remain = bar_size % buf_size;
> + if (remain)
> + if (pci_endpoint_test_bar_memcmp(test, barno, buf_size * iters,
> + write_buf, read_buf, remain))
> return false;
> - }
>
> return true;
> }
> --
> 2.44.0
>
--
மணிவண்ணன் சதாசிவம்
next prev parent reply other threads:[~2024-05-04 14:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-22 16:41 [PATCH v4] misc: pci_endpoint_test: Use memcpy_toio()/memcpy_fromio() for BAR tests Niklas Cassel
2024-03-22 17:03 ` Kuppuswamy Sathyanarayanan
2024-03-25 7:58 ` Niklas Cassel
2024-04-18 9:08 ` Niklas Cassel
2024-04-18 17:49 ` Kuppuswamy Sathyanarayanan
2024-05-04 14:34 ` Manivannan Sadhasivam [this message]
2024-05-17 10:09 ` Krzysztof Wilczyński
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240504143451.GA4315@thinkpad \
--to=manivannan.sadhasivam@linaro.org \
--cc=arnd@arndb.de \
--cc=cassel@kernel.org \
--cc=dlemoal@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=kishon@kernel.org \
--cc=kw@linux.com \
--cc=linux-pci@vger.kernel.org \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).