From: "Gonzalez Monroy, Sergio" <sergio.gonzalez.monroy@intel.com>
To: Jay Rolette <rolette@infiniteio.com>
Cc: DPDK <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v1] change hugepage sorting to avoid overlapping memcpy
Date: Tue, 08 Sep 2015 15:24:26 +0100 [thread overview]
Message-ID: <55EEEF99.2000708@intel.com> (raw)
In-Reply-To: <CADNuJVprhcF455jk3Z=siGQLEqq_iP_Za6KAtTou4p6LYe_YKQ@mail.gmail.com>
On 08/09/2015 14:29, Jay Rolette wrote:
> Most of the code in sort_by_physaddr() should be replaced by a call to
> qsort() instead. Less code and gets rid of an O(n^2) sort. It's only
> init code, but given how long EAL init takes, every bit helps.
>
Fair enough.
Actually, we already use qsort in
lib/librte_eal/linuxapp/eal/eal_hugeapge_info.c
> I submitted a patch for this close to a year ago:
> http://dpdk.org/dev/patchwork/patch/2061/
>
I just had a quick look at it and seems to be archived with 'Changes
Requested' status.
I will comment on it.
Sergio
> Jay
>
> On Tue, Sep 8, 2015 at 7:45 AM, Gonzalez Monroy, Sergio
> <sergio.gonzalez.monroy@intel.com
> <mailto:sergio.gonzalez.monroy@intel.com>> wrote:
>
> Hi Ralf,
>
> Just a few comments/suggestions:
>
> Add 'eal/linux:' to the commit title, ie:
> "eal/linux: change hugepage sorting to avoid overlapping memcpy"
>
> On 04/09/2015 11:14, Ralf Hoffmann wrote:
>
> with only one hugepage or already sorted hugepage addresses,
> the sort
> function called memcpy with same src and dst pointer.
> Debugging with
> valgrind will issue a warning about overlapping area. This
> patch changes
> the bubble sort to avoid this behavior. Also, the function
> cannot fail
> any longer.
>
> Signed-off-by: Ralf Hoffmann
> <ralf.hoffmann@allegro-packets.com
> <mailto:ralf.hoffmann@allegro-packets.com>>
> ---
> lib/librte_eal/linuxapp/eal/eal_memory.c | 27
> +++++++++++++--------------
> 1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c
> index ac2745e..6d01f61 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -699,25 +699,25 @@ error:
> * higher address first on powerpc). We use a slow
> algorithm, but we won't
> * have millions of pages, and this is only done at init time.
> */
> -static int
> +static void
> sort_by_physaddr(struct hugepage_file *hugepg_tbl, struct
> hugepage_info *hpi)
> {
> unsigned i, j;
> - int compare_idx;
> + unsigned compare_idx;
> uint64_t compare_addr;
> struct hugepage_file tmp;
> for (i = 0; i < hpi->num_pages[0]; i++) {
> - compare_addr = 0;
> - compare_idx = -1;
> + compare_addr = hugepg_tbl[i].physaddr;
> + compare_idx = i;
> /*
> - * browse all entries starting at 'i', and
> find the
> + * browse all entries starting at 'i+1', and
> find the
> * entry with the smallest addr
> */
> - for (j=i; j< hpi->num_pages[0]; j++) {
> + for (j=i + 1; j < hpi->num_pages[0]; j++) {
>
> Although there are many style/checkpatch issues in current code,
> we try to fix them
> in new patches.
> In that regard, checkpatch complains about above line with:
> ERROR:SPACING: spaces required around that '='
>
> - if (compare_addr == 0 ||
> + if (
> #ifdef RTE_ARCH_PPC_64
> hugepg_tbl[j].physaddr >
> compare_addr) {
> #else
> @@ -728,10 +728,9 @@ sort_by_physaddr(struct hugepage_file
> *hugepg_tbl, struct hugepage_info *hpi)
> }
> }
> - /* should not happen */
> - if (compare_idx == -1) {
> - RTE_LOG(ERR, EAL, "%s(): error in
> physaddr sorting\n", __func__);
> - return -1;
> + if (compare_idx == i) {
> + /* no smaller page found */
> + continue;
> }
> /* swap the 2 entries in the table */
> @@ -741,7 +740,8 @@ sort_by_physaddr(struct hugepage_file
> *hugepg_tbl, struct hugepage_info *hpi)
> sizeof(struct hugepage_file));
> memcpy(&hugepg_tbl[i], &tmp, sizeof(struct
> hugepage_file));
> }
> - return 0;
> +
> + return;
> }
>
> I reckon checkpatch is not picking this one because the
> end-of-function is not part of the patch,
> but it is a warning:
> WARNING:RETURN_VOID: void function return statements are not
> generally useful
>
> /*
> @@ -1164,8 +1164,7 @@ rte_eal_hugepage_init(void)
> goto fail;
> }
> - if (sort_by_physaddr(&tmp_hp[hp_offset], hpi) < 0)
> - goto fail;
> + sort_by_physaddr(&tmp_hp[hp_offset], hpi);
> #ifdef RTE_EAL_SINGLE_FILE_SEGMENTS
> /* remap all hugepages into single file
> segments */
>
>
>
> Thanks,
> Sergio
>
>
next prev parent reply other threads:[~2015-09-08 14:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-04 10:14 Ralf Hoffmann
2015-09-08 12:45 ` Gonzalez Monroy, Sergio
2015-09-08 13:29 ` Jay Rolette
2015-09-08 14:24 ` Gonzalez Monroy, Sergio [this message]
2016-01-05 9:25 ` [dpdk-dev] [PATCH v2 0/1] " Ralf Hoffmann
2016-01-05 9:25 ` [dpdk-dev] [PATCH v2 1/1] " Ralf Hoffmann
2016-01-05 9:37 ` [dpdk-dev] [PATCH v3 0/1] eal/linux: " Ralf Hoffmann
2016-01-05 9:37 ` [dpdk-dev] [PATCH v3 1/1] " Ralf Hoffmann
2016-01-07 9:33 ` Sergio Gonzalez Monroy
2016-01-07 9:51 ` Sergio Gonzalez Monroy
2016-01-07 10:38 ` Sergio Gonzalez Monroy
2016-01-07 13:58 ` Ralf Hoffmann
2016-01-07 13:59 ` [dpdk-dev] [PATCH v4 1/1] " Ralf Hoffmann
2016-01-07 14:36 ` Sergio Gonzalez Monroy
2016-01-07 14:54 ` [dpdk-dev] [PATCH v5 1/1] eal/linux: " Ralf Hoffmann
2016-03-02 16:13 ` Thomas Monjalon
2015-09-09 8:41 ` [dpdk-dev] [PATCH v1] " Ralf Hoffmann
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